really generic, type save and type definable.

really generic, type save and type definable.

[stefani]

The API is still stable, no code which use the current  kfifo API must 
be modified!

Here are the results of the text section usage:

Example 1:
                        kfifo_put/_get  kfifo_in/out    current kfifo
dynamic allocated       0x000002a8      0x00000291      0x00000299
in place                0x00000291      0x0000026e      0x00000273

kfifo.c                 new             old
text section size       0x00000be5      0x000008b2

As you can see, kfifo_put/kfifo_get creates a little bit more code than 
kfifo_in/kfifo_out, but it is much faster (the code is inline).

The code is complete hand crafted and optimized. The text section size is as 
small as possible. You get all the fifo handling in only 3 kb. This includes 
type safe fix size records, dynamic records and DMA handling.

This should be the final version. All requested features are implemented.

Note: Most features of this API doesn't have any users. All functions which
are not used in the next 9 months will be removed. So, please adapt your
drivers and other sources as soon as possible to the new API and post it. 

This are the features which are currently not used in the kernel:

kfifo_to_user()
kfifo_from_user()
kfifo_dma_....() macros
kfifo_esize()
kfifo_recsize()
kfifo_put()
kfifo_get()
the fixed size record elements, exclude "unsigned char" fifo's and
the variable size records fifo's

ChangeLog:

12.05.2010 Sync with kernel 2.6.34-rc7
20.04.2010 Fix possible break of the kernel build by the patch sequence
18.04.2010 Sync with kernel 2.6.34-rc4
12.02.2010 Sync with kernel 2.6.33-rc7
           Add example code to the kernel sample directory
           Make more exact comments for the kerneldoc tools
           Split the patch
05.02.2010 Sync with kernel 2.6.33-rc6
           Fix comments for the kerneldoc tools
           Fix kernel-api.tmpl
           Checked with sparse
           Tested and analize with gcc-3.4.6
           Fix INIT_KFIFO to create better code
           make checkpath.pl clean
           add some comments for better understanding the code
           rename kfifo_out_locked() into kfifo_out_spinlocked() and add an
           alias kfifo_out_locked() for kfifo_out_spinlocked() which will be
           removed in future.
           Did the same for kfifo_in_locked()
           Fix kfifo_free to free the fifo buffer, not the fifo structure
           Add all fixes suggested by Andrew Morton
           Modify test1.c sample code
27.01.2010 renamed kfifo_sizeof into kfifo_esize
           code refactoring: shrink foot print 
           fix bugs
           changed all 0 pointer into NULL
           fix a miss use in drivers/char/nozomi.c
           enhanced DMA functions to handle a non continues fifo buffer (e.g. vmalloc)
           reintroduced record dynamic handling as requested (tried to implemented it 
           separately, but this will double the code)
           Sync with kernel 2.6.33-rc5           
16.01.2010 Kicked away dynamic record handling. If anybody want it please let me know.
           Add a esize field which represents the size of the element stored in
           the fifo. This will increase the size of the fifo stucture by 4 bytes 
           but obtain a smaller code.
           Generalized the kfifo.c funtions to handle byte and all other element 
           sizes in common functions.
           Shrink the code size of kfifo.c from 2k to 1k
           Code cleanup
15.01.2010 fix kfifo_dma_*() bugs
           add a DMA usage exmaple
           fix kfifo_free()
           prevent creation of fifo with less then 2 entries
           prevent a real in place fifo manipulation with kfifo_alloc(), 
           kfifo_init() or kfifo_free()
           make INIT_KFIFO save with a dynamic allocated fifo
14.01.2010 Change the size field of the fifo structure into a mask field, which
           is size - 1. This will save some instructions 
           Make the basic structure mode generic. Add a data pointer and mask
           field, also for real in place fifo, because the extra function parameter
           passing of the data pointer and and the fifo size was to costly
           Change all internal functions to work with the generic base structure
           Optimized the kfifo_put and kfifo_get macros to prevent an indirection
           Code cleanup
           Bug fixes in kfifo_dma_* macros
           Update examples
           Sync with kernel 2.6.33-rc4
06.01.2010 Add a note about locking: clarify when locking is needed
           Fix byte stream example
           Remove unnecessary typedefs
           Make checkpatch.pl clean: one error left, but there is no way to
           solve this...
28.12.2009 Sanitize kfifo_*_user() error handling (suggested by Andi Kleen)
           kfifo_from_user() and kfifo_to_user() will now return an error
           code and the number of copied bytes will be stored in a variable
           passed as pointer
           Make patch readable
           Update examples
           Fix a typo
27.12.2009 Sync with kernel 2.6.33-rc2
           Introduce new kfifo_initialized macro (suggested by Andi Kleen)
           Renamed kfifo_peek into kfifo_peek_len
           Introduce new kfifo_peek macro (suggest by Andi Kleen)
           Introduce new kfifo_out_peek macro (suggested by Andi Kleen)
           Fix broken kernel-doc notation
           Fix samples
21.12.2009 Fix checkpatch.pl, fix samples
20.12.2009 Bug fixing
           Fix samples
19.12.2009 First draft
13.12.2009 First implementation of a type safe fifo implementation, called kqueue

There are different types of a fifo which can not handled in C without a
lot of overhead. So i decided to write the API as a set of macros, which 
is the only way to do a kind of template meta programming without C++. 
This macros handles the different types of fifos in a transparent way.

There are a lot of benefits:

- Compile time handling of the different fifo types
- Better performance (a save put or get of an integer does only generate 
  9 assembly instructions on a x86) 
- Type save
- Cleaner interface, the additional kfifo_..._rec() functions are gone
- Easier to use
- Less error prone
- Different types of fifos: it is now possible to define a int fifo or
  any other type. See below for an example.
- Smaller footprint for none byte type fifos
- No need of creating a second hidden variable, like in the old DEFINE_KFIFO

The API was not changed.

There are now real in place fifos where the data space is a part of the 
structure. The fifo needs now 20 byte plus the fifo space. Dynamic 
assigned or allocated create a little bit more code.

Most of the macros code will be optimized away and simple generate a 
function call. Only the really small one generates inline code.

Additional you can now create fifos for any data type, not only the
"unsigned char" byte streamed fifos.

There is also a new kfifo_put and kfifo_get function, to handle a single
element in a fifo. This macros generates inline code, which is lit bit
larger but faster.

I know that this kind of macros are very sophisticated and not easy to
maintain. But i have all tested and it works as expected. I analyzed the
output of the compiler and for the x86 the code is as good as hand
written assembler code. For the byte stream fifo the generate code is exact 
the same as with the current kfifo implementation. For all other types of
fifos the code is smaller before, because the interface is easier to use. 

The main goal was to provide an API which is very intuitive, save and easy
to use. So linux will get now a powerful fifo API which provides all what 
a developer needs. This will save in the future a lot of kernel space, since
there is no need to write an own implementation. Most of the device driver 
developers need a fifo, and also deep kernel development will gain benefit 
from this API.

This code is ready for merge into the mm tree or linux next. Please review 
it and merge.

Stefani

[PATCH 1/4] fix kfifo miss use of nozami.c

[stefani]

From: Stefani Seibold <stefani@seibold.net>

User of the kernel fifo should never bypass the API and directly access
the fifo structure. Otherwise it will be very hard to maintain the API.

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
 drivers/char/nozomi.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/drivers/char/nozomi.c b/drivers/char/nozomi.c
index a663800..d578449 100644
--- a/drivers/char/nozomi.c
+++ b/drivers/char/nozomi.c
@@ -1741,8 +1741,7 @@ static int ntty_write_room(struct tty_struct *tty)
 	if (dc) {
 		mutex_lock(&port->tty_sem);
 		if (port->port.count)
-			room = port->fifo_ul.size -
-					kfifo_len(&port->fifo_ul);
+			room = kfifo_avail(&port->fifo_ul);
 		mutex_unlock(&port->tty_sem);
 	}
 	return room;
-- 
1.7.0.4

[PATCH 2/4] add the new generic kfifo API

[stefani]

From: Stefani Seibold <stefani@seibold.net>

add the new version of the kfifo API files kfifo.c and kfifo.h.

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
 include/linux/kfifo-new.h |  844 +++++++++++++++++++++++++++++++++++++++++++++
 kernel/kfifo-new.c        |  602 ++++++++++++++++++++++++++++++++
 2 files changed, 1446 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/kfifo-new.h
 create mode 100644 kernel/kfifo-new.c

diff --git a/include/linux/kfifo-new.h b/include/linux/kfifo-new.h
new file mode 100644
index 0000000..311f875
--- /dev/null
+++ b/include/linux/kfifo-new.h
@@ -0,0 +1,844 @@
+/*
+ * A generic kernel FIFO implementation
+ *
+ * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#ifndef _LINUX_KFIFO_H
+#define _LINUX_KFIFO_H
+
+/*
+ * How to porting drivers to the new generic FIFO API:
+ *
+ * - Modify the declaration of the "struct kfifo *" object into a
+ *   in-place "struct kfifo" object
+ * - Init the in-place object with kfifo_alloc() or kfifo_init()
+ *   Note: The address of the in-place "struct kfifo" object must be
+ *   passed as the first argument to this functions
+ * - Replace the use of __kfifo_put into kfifo_in and __kfifo_get
+ *   into kfifo_out
+ * - Replace the use of kfifo_put into kfifo_in_spinlocked and kfifo_get
+ *   into kfifo_out_spinlocked
+ *   Note: the spinlock pointer formerly passed to kfifo_init/kfifo_alloc
+ *   must be passed now to the kfifo_in_spinlocked and kfifo_out_spinlocked
+ *   as the last parameter
+ * - The formerly __kfifo_* functions are renamed into kfifo_*
+ */
+
+/*
+ * Note about locking : There is no locking required until only * one reader
+ * and one writer is using the fifo and no kfifo_reset() will be * called
+ *  kfifo_reset_out() can be safely used, until it will be only called
+ * in the reader thread.
+ *  For multiple writer and one reader there is only a need to lock the writer.
+ * And vice versa for only one writer and multiple reader there is only a need
+ * to lock the reader.
+ */
+
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/stddef.h>
+#include <linux/scatterlist.h>
+
+struct __kfifo {
+	unsigned int	in;
+	unsigned int	out;
+	unsigned int	mask;
+	unsigned int	esize;
+	void		*data;
+};
+
+#define __STRUCT_KFIFO_COMMON(datatype, recsize, ptrtype) \
+	union { \
+		struct __kfifo	kfifo; \
+		datatype	*type; \
+		char		(*rectype)[recsize]; \
+		ptrtype		*ptr; \
+		const ptrtype	*ptr_const; \
+	}
+
+#define __STRUCT_KFIFO(type, size, recsize, ptrtype) \
+{ \
+	__STRUCT_KFIFO_COMMON(type, recsize, ptrtype); \
+	type		buf[((size < 2) || (size & (size - 1))) ? -1 : size]; \
+}
+
+#define STRUCT_KFIFO(type, size) \
+	struct __STRUCT_KFIFO(type, size, 0, type)
+
+#define __STRUCT_KFIFO_PTR(type, recsize, ptrtype) \
+{ \
+	__STRUCT_KFIFO_COMMON(type, recsize, ptrtype); \
+	type		buf[0]; \
+}
+
+#define STRUCT_KFIFO_PTR(type) \
+	struct __STRUCT_KFIFO_PTR(type, 0, type)
+
+/*
+ * define compatibility "struct kfifo" for dynamic allocated fifos
+ */
+struct kfifo __STRUCT_KFIFO_PTR(unsigned char, 0, void);
+
+#define STRUCT_KFIFO_REC_1(size) \
+	struct __STRUCT_KFIFO(unsigned char, size, 1, void)
+
+#define STRUCT_KFIFO_REC_2(size) \
+	struct __STRUCT_KFIFO(unsigned char, size, 2, void)
+
+/*
+ * define kfifo_rec types
+ */
+struct kfifo_rec_ptr_1 __STRUCT_KFIFO_PTR(unsigned char, 1, void);
+struct kfifo_rec_ptr_2 __STRUCT_KFIFO_PTR(unsigned char, 2, void);
+
+/*
+ * helper macro to distinguish between real in place fifo where the fifo
+ * array is a part of the structure and the fifo type where the array is
+ * outside of the fifo structure.
+ */
+#define	__is_kfifo_ptr(fifo)	(sizeof(*fifo) == sizeof(struct __kfifo))
+
+/**
+ * DECLARE_KFIFO_PTR - macro to declare a fifo pointer object
+ * @fifo: name of the declared fifo
+ * @type: type of the fifo elements
+ */
+#define DECLARE_KFIFO_PTR(fifo, type)	STRUCT_KFIFO_PTR(type) fifo
+
+/**
+ * DECLARE_KFIFO - macro to declare a fifo object
+ * @fifo: name of the declared fifo
+ * @type: type of the fifo elements
+ * @size: the number of elements in the fifo, this must be a power of 2
+ */
+#define DECLARE_KFIFO(fifo, type, size)	STRUCT_KFIFO(type, size) fifo
+
+/**
+ * INIT_KFIFO - Initialize a fifo declared by DECLARE_KFIFO
+ * @fifo: name of the declared fifo datatype
+ */
+#define INIT_KFIFO(fifo) \
+(void)({ \
+	typeof(&(fifo)) __tmp = &(fifo); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	__kfifo->in = 0; \
+	__kfifo->out = 0; \
+	__kfifo->mask = __is_kfifo_ptr(__tmp) ? 0 : ARRAY_SIZE(__tmp->buf) - 1;\
+	__kfifo->esize = sizeof(*__tmp->buf); \
+	__kfifo->data = __is_kfifo_ptr(__tmp) ?  NULL : __tmp->buf; \
+})
+
+/**
+ * DEFINE_KFIFO - macro to define and initialize a fifo
+ * @fifo: name of the declared fifo datatype
+ * @type: type of the fifo elements
+ * @size: the number of elements in the fifo, this must be a power of 2
+ *
+ * Note: the macro can be used for global and local fifo data type variables.
+ */
+#define DEFINE_KFIFO(fifo, type, size) \
+	DECLARE_KFIFO(fifo, type, size) = \
+	(typeof(fifo)) { \
+		{ \
+			{ \
+			.in	= 0, \
+			.out	= 0, \
+			.mask	= __is_kfifo_ptr(&(fifo)) ? \
+				  0 : \
+				  ARRAY_SIZE((fifo).buf) - 1, \
+			.esize	= sizeof(*(fifo).buf), \
+			.data	= __is_kfifo_ptr(&(fifo)) ? \
+				NULL : \
+				(fifo).buf, \
+			} \
+		} \
+	}
+
+
+static inline unsigned int __must_check
+__kfifo_must_check_helper(unsigned int val)
+{
+	return val;
+}
+
+/**
+ * kfifo_initialized - Check if the fifo is initialized
+ * @fifo: address of the fifo to check
+ *
+ * Return %true if fifo is initialized, otherwise %false.
+ * Assumes the fifo was 0 before.
+ */
+#define kfifo_initialized(fifo) ((fifo)->kfifo.mask)
+
+/**
+ * kfifo_esize - returns the size of the element managed by the fifo
+ * @fifo: address of the fifo to be used
+ */
+#define kfifo_esize(fifo)	((fifo)->kfifo.esize)
+
+/**
+ * kfifo_recsize - returns the size of the record length field
+ * @fifo: address of the fifo to be used
+ */
+#define kfifo_recsize(fifo)	(sizeof(*(fifo)->rectype))
+
+/**
+ * kfifo_size - returns the size of the fifo in elements
+ * @fifo: address of the fifo to be used
+ */
+#define kfifo_size(fifo)	((fifo)->kfifo.mask + 1)
+
+/**
+ * kfifo_reset - removes the entire fifo content
+ * @fifo: address of the fifo to be used
+ *
+ * Note: usage of kfifo_reset() is dangerous. It should be only called when the
+ * fifo is exclusived locked or when it is secured that no other thread is
+ * accessing the fifo.
+ */
+#define kfifo_reset(fifo) \
+(void)({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	__tmp->kfifo.in = __tmp->kfifo.out = 0; \
+})
+
+/**
+ * kfifo_reset_out - skip fifo content
+ * @fifo: address of the fifo to be used
+ *
+ * Note: The usage of kfifo_reset_out() is safe until it will be only called
+ * from the reader thread and there is only one concurrent reader. Otherwise
+ * it is dangerous and must be handled in the same way as kfifo_reset().
+ */
+#define kfifo_reset_out(fifo)	\
+(void)({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	__tmp->kfifo.out = __tmp->kfifo.in; \
+})
+
+/**
+ * kfifo_len - returns the number of used elements in the fifo
+ * @fifo: address of the fifo to be used
+ */
+#define kfifo_len(fifo) \
+({ \
+	typeof(fifo + 1) __tmpl = (fifo); \
+	__tmpl->kfifo.in - __tmpl->kfifo.out; \
+})
+
+/**
+ * kfifo_is_empty - returns true if the fifo is empty
+ * @fifo: address of the fifo to be used
+ */
+#define	kfifo_is_empty(fifo) \
+({ \
+	typeof(fifo + 1) __tmpq = (fifo); \
+	__tmpq->kfifo.in == __tmpq->kfifo.out; \
+})
+
+/**
+ * kfifo_is_full - returns true if the fifo is full
+ * @fifo: address of the fifo to be used
+ */
+#define	kfifo_is_full(fifo) \
+({ \
+	typeof(fifo + 1) __tmpq = (fifo); \
+	kfifo_len(__tmpq) > __tmpq->kfifo.mask; \
+})
+
+/**
+ * kfifo_avail - returns the number of unused elements in the fifo
+ * @fifo: address of the fifo to be used
+ */
+#define	kfifo_avail(fifo) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmpq = (fifo); \
+	const size_t __recsize = sizeof(*__tmpq->rectype); \
+	unsigned int __avail = kfifo_size(__tmpq) - kfifo_len(__tmpq); \
+	(__recsize) ? ((__avail <= __recsize) ? 0 : \
+	__kfifo_max_r(__avail - __recsize, __recsize)) : \
+	__avail; \
+}) \
+)
+
+/**
+ * kfifo_skip - skip output data
+ * @fifo: address of the fifo to be used
+ */
+#define	kfifo_skip(fifo) \
+(void)({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (__recsize) \
+		__kfifo_skip_r(__kfifo, __recsize); \
+	else \
+		__kfifo->out++; \
+})
+
+/**
+ * kfifo_peek_len - gets the size of the next fifo record
+ * @fifo: address of the fifo to be used
+ *
+ * This function returns the size of the next fifo record in number of bytes.
+ */
+#define kfifo_peek_len(fifo) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	(!__recsize) ? kfifo_len(__tmp) * sizeof(*__tmp->type) : \
+	__kfifo_len_r(__kfifo, __recsize); \
+}) \
+)
+
+/**
+ * kfifo_alloc - dynamically allocates a new fifo buffer
+ * @fifo: pointer to the fifo
+ * @size: the number of elements in the fifo, this must be a power of 2
+ * @gfp_mask: get_free_pages mask, passed to kmalloc()
+ *
+ * This macro dynamically allocates a new fifo buffer.
+ *
+ * The numer of elements will be rounded-up to a power of 2.
+ * The fifo will be release with kfifo_free().
+ * Return 0 if no error, otherwise an error code.
+ */
+#define kfifo_alloc(fifo, size, gfp_mask) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	__is_kfifo_ptr(__tmp) ? \
+	__kfifo_alloc(__kfifo, size, sizeof(*__tmp->type), gfp_mask) : \
+	-EINVAL; \
+}) \
+)
+
+/**
+ * kfifo_free - frees the fifo
+ * @fifo: the fifo to be freed
+ */
+#define kfifo_free(fifo) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (__is_kfifo_ptr(__tmp)) \
+		__kfifo_free(__kfifo); \
+})
+
+/**
+ * kfifo_init - initialize a fifo using a preallocated buffer
+ * @fifo: the fifo to assign the buffer
+ * @buffer: the preallocated buffer to be used
+ * @size: the size of the internal buffer, this have to be a power of 2
+ *
+ * This macro initialize a fifo using a preallocated buffer.
+ *
+ * The numer of elements will be rounded-up to a power of 2.
+ * Return 0 if no error, otherwise an error code.
+ */
+#define kfifo_init(fifo, buffer, size) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	__is_kfifo_ptr(__tmp) ? \
+	__kfifo_init(__kfifo, buffer, size, sizeof(*__tmp->type)) : \
+	-EINVAL; \
+})
+
+/**
+ * kfifo_put - put data into the fifo
+ * @fifo: address of the fifo to be used
+ * @val: the data to be added
+ *
+ * This macro copies the given value into the fifo.
+ * It returns 0 if the fifo was full. Otherwise it returns the number
+ * processed elements.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_put(fifo, val) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(val + 1) __val = (val); \
+	unsigned int __ret; \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) { \
+		typeof(__tmp->ptr_const) __dummy __attribute__ ((unused)); \
+		__dummy = (typeof(__val))NULL; \
+	} \
+	if (__recsize) \
+		__ret = __kfifo_in_r(__kfifo, __val, sizeof(*__val), \
+			__recsize); \
+	else { \
+		__ret = !kfifo_is_full(__tmp); \
+		if (__ret) { \
+			(__is_kfifo_ptr(__tmp) ? \
+			((typeof(__tmp->type))__kfifo->data) : \
+			(__tmp->buf) \
+			)[__kfifo->in & __tmp->kfifo.mask] = \
+				*(typeof(__tmp->type))__val; \
+			smp_wmb(); \
+			__kfifo->in++; \
+		} \
+	} \
+	__ret; \
+})
+
+/**
+ * kfifo_get - get data from the fifo
+ * @fifo: address of the fifo to be used
+ * @val: the var where to store the data to be added
+ *
+ * This macro reads the data from the fifo.
+ * It returns 0 if the fifo was empty. Otherwise it returns the number
+ * processed elements.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_get(fifo, val) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(val + 1) __val = (val); \
+	unsigned int __ret; \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) \
+		__val = (typeof(__tmp->ptr))0; \
+	if (__recsize) \
+		__ret = __kfifo_out_r(__kfifo, __val, sizeof(*__val), \
+			__recsize); \
+	else { \
+		__ret = !kfifo_is_empty(__tmp); \
+		if (__ret) { \
+			*(typeof(__tmp->type))__val = \
+				(__is_kfifo_ptr(__tmp) ? \
+				((typeof(__tmp->type))__kfifo->data) : \
+				(__tmp->buf) \
+				)[__kfifo->out & __tmp->kfifo.mask]; \
+			smp_wmb(); \
+			__kfifo->out++; \
+		} \
+	} \
+	__ret; \
+}) \
+)
+
+/**
+ * kfifo_peek - get data from the fifo without removing
+ * @fifo: address of the fifo to be used
+ * @val: the var where to store the data to be added
+ *
+ * This reads the data from the fifo without removing it from the fifo.
+ * It returns 0 if the fifo was empty. Otherwise it returns the number
+ * processed elements.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_peek(fifo, val) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(val + 1) __val = (val); \
+	unsigned int __ret; \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) \
+		__val = (typeof(__tmp->ptr))NULL; \
+	if (__recsize) \
+		__ret = __kfifo_out_peek_r(__kfifo, __val, sizeof(*__val), \
+			__recsize); \
+	else { \
+		__ret = !kfifo_is_empty(__tmp); \
+		if (__ret) { \
+			*(typeof(__tmp->type))__val = \
+				(__is_kfifo_ptr(__tmp) ? \
+				((typeof(__tmp->type))__kfifo->data) : \
+				(__tmp->buf) \
+				)[__kfifo->out & __tmp->kfifo.mask]; \
+			smp_wmb(); \
+		} \
+	} \
+	__ret; \
+}) \
+)
+
+/**
+ * kfifo_in - put data into the fifo
+ * @fifo: address of the fifo to be used
+ * @buf: the data to be added
+ * @n: number of elements to be added
+ *
+ * This macro copies the given buffer into the fifo and returns the
+ * number of copied elements.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_in(fifo, buf, n) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(buf + 1) __buf = (buf); \
+	unsigned long __n = (n); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) { \
+		typeof(__tmp->ptr_const) __dummy __attribute__ ((unused)); \
+		__dummy = (typeof(__buf))NULL; \
+	} \
+	(__recsize) ?\
+	__kfifo_in_r(__kfifo, __buf, __n, __recsize) : \
+	__kfifo_in(__kfifo, __buf, __n); \
+})
+
+/**
+ * kfifo_in_spinlocked - put data into the fifo using a spinlock for locking
+ * @fifo: address of the fifo to be used
+ * @buf: the data to be added
+ * @n: number of elements to be added
+ * @lock: pointer to the spinlock to use for locking
+ *
+ * This macro copies the given values buffer into the fifo and returns the
+ * number of copied elements.
+ */
+#define	kfifo_in_spinlocked(fifo, buf, n, lock) \
+({ \
+	unsigned long __flags; \
+	unsigned int __ret; \
+	spin_lock_irqsave(lock, __flags); \
+	__ret = kfifo_in(fifo, buf, n); \
+	spin_unlock_irqrestore(lock, __flags); \
+	__ret; \
+})
+
+/* alias for kfifo_in_spinlocked, will be removed in a future release */
+#define kfifo_in_locked(fifo, buf, n, lock) \
+		kfifo_in_spinlocked(fifo, buf, n, lock)
+
+/**
+ * kfifo_out - get data from the fifo
+ * @fifo: address of the fifo to be used
+ * @buf: pointer to the storage buffer
+ * @n: max. number of elements to get
+ *
+ * This macro get some data from the fifo and return the numbers of elements
+ * copied.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_out(fifo, buf, n) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(buf + 1) __buf = (buf); \
+	unsigned long __n = (n); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) { \
+		typeof(__tmp->ptr) __dummy = NULL; \
+		__buf = __dummy; \
+	} \
+	(__recsize) ?\
+	__kfifo_out_r(__kfifo, __buf, __n, __recsize) : \
+	__kfifo_out(__kfifo, __buf, __n); \
+}) \
+)
+
+/**
+ * kfifo_out_spinlocked - get data from the fifo using a spinlock for locking
+ * @fifo: address of the fifo to be used
+ * @buf: pointer to the storage buffer
+ * @n: max. number of elements to get
+ * @lock: pointer to the spinlock to use for locking
+ *
+ * This macro get the data from the fifo and return the numbers of elements
+ * copied.
+ */
+#define	kfifo_out_spinlocked(fifo, buf, n, lock) \
+__kfifo_must_check_helper( \
+({ \
+	unsigned long __flags; \
+	unsigned int __ret; \
+	spin_lock_irqsave(lock, __flags); \
+	__ret = kfifo_out(fifo, buf, n); \
+	spin_unlock_irqrestore(lock, __flags); \
+	__ret; \
+}) \
+)
+
+/* alias for kfifo_out_spinlocked, will be removed in a future release */
+#define kfifo_out_locked(fifo, buf, n, lock) \
+		kfifo_out_spinlocked(fifo, buf, n, lock)
+
+/**
+ * kfifo_from_user - puts some data from user space into the fifo
+ * @fifo: address of the fifo to be used
+ * @from: pointer to the data to be added
+ * @len: the length of the data to be added
+ * @copied: pointer to output variable to store the number of copied bytes
+ *
+ * This macro copies at most @len bytes from the @from into the
+ * fifo, depending of the available space and returns -EFAULT/0.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_from_user(fifo, from, len, copied) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	const void __user *__from = (from); \
+	unsigned int __len = (len); \
+	unsigned int *__copied = (copied); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	(__recsize) ? \
+	__kfifo_from_user_r(__kfifo, __from, __len,  __copied, __recsize) : \
+	__kfifo_from_user(__kfifo, __from, __len, __copied); \
+}) \
+)
+
+/**
+ * kfifo_to_user - copies data from the fifo into user space
+ * @fifo: address of the fifo to be used
+ * @to: where the data must be copied
+ * @len: the size of the destination buffer
+ * @copied: pointer to output variable to store the number of copied bytes
+ *
+ * This macro copies at most @len bytes from the fifo into the
+ * @to buffer and returns -EFAULT/0.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_to_user(fifo, to, len, copied) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	void __user *__to = (to); \
+	unsigned int __len = (len); \
+	unsigned int *__copied = (copied); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	(__recsize) ? \
+	__kfifo_to_user_r(__kfifo, __to, __len, __copied, __recsize) : \
+	__kfifo_to_user(__kfifo, __to, __len, __copied); \
+}) \
+)
+
+/**
+ * kfifo_dma_in_prepare - setup a scatterlist for DMA input
+ * @fifo: address of the fifo to be used
+ * @sgl: pointer to the scatterlist array
+ * @nents: number of entries in the scatterlist array
+ * @len: number of elements to transfer
+ *
+ * This macro fills a scatterlist for DMA input.
+ * It returns the number entries in the scatterlist array.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macros.
+ */
+#define	kfifo_dma_in_prepare(fifo, sgl, nents, len) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	struct scatterlist *__sgl = (sgl); \
+	int __nents = (nents); \
+	unsigned int __len = (len); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	(__recsize) ? \
+	__kfifo_dma_in_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) : \
+	__kfifo_dma_in_prepare(__kfifo, __sgl, __nents, __len); \
+})
+
+/**
+ * kfifo_dma_in_finish - finish a DMA IN operation
+ * @fifo: address of the fifo to be used
+ * @len: number of bytes to received
+ *
+ * This macro finish a DMA IN operation. The in counter will be updated by
+ * the len parameter. No error checking will be done.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macros.
+ */
+#define kfifo_dma_in_finish(fifo, len) \
+(void)({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	unsigned int __len = (len); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (__recsize) \
+		__kfifo_dma_in_finish_r(__kfifo, __len, __recsize); \
+	else \
+		__kfifo->in += __len / sizeof(*__tmp->type); \
+})
+
+/**
+ * kfifo_dma_out_prepare - setup a scatterlist for DMA output
+ * @fifo: address of the fifo to be used
+ * @sgl: pointer to the scatterlist array
+ * @nents: number of entries in the scatterlist array
+ * @len: number of elements to transfer
+ *
+ * This macro fills a scatterlist for DMA output which at most @len bytes
+ * to transfer.
+ * It returns the number entries in the scatterlist array.
+ * A zero means there is no space available and the scatterlist is not filled.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macros.
+ */
+#define	kfifo_dma_out_prepare(fifo, sgl, nents, len) \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	struct scatterlist *__sgl = (sgl); \
+	int __nents = (nents); \
+	unsigned int __len = (len); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	(__recsize) ? \
+	__kfifo_dma_out_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) : \
+	__kfifo_dma_out_prepare(__kfifo, __sgl, __nents, __len); \
+})
+
+/**
+ * kfifo_dma_out_finish - finish a DMA OUT operation
+ * @fifo: address of the fifo to be used
+ * @len: number of bytes transferd
+ *
+ * This macro finish a DMA OUT operation. The out counter will be updated by
+ * the len parameter. No error checking will be done.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macros.
+ */
+#define kfifo_dma_out_finish(fifo, len) \
+(void)({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	unsigned int __len = (len); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (__recsize) \
+		__kfifo_dma_out_finish_r(__kfifo, __recsize); \
+	else \
+		__kfifo->out += __len / sizeof(*__tmp->type); \
+})
+
+/**
+ * kfifo_out_peek - gets some data from the fifo
+ * @fifo: address of the fifo to be used
+ * @buf: pointer to the storage buffer
+ * @n: max. number of elements to get
+ *
+ * This macro get the data from the fifo and return the numbers of elements
+ * copied. The data is not removed from the fifo.
+ *
+ * Note that with only one concurrent reader and one concurrent
+ * writer, you don't need extra locking to use these macro.
+ */
+#define	kfifo_out_peek(fifo, buf, n) \
+__kfifo_must_check_helper( \
+({ \
+	typeof(fifo + 1) __tmp = (fifo); \
+	typeof(buf + 1) __buf = (buf); \
+	unsigned long __n = (n); \
+	const size_t __recsize = sizeof(*__tmp->rectype); \
+	struct __kfifo *__kfifo = &__tmp->kfifo; \
+	if (0) { \
+		typeof(__tmp->ptr) __dummy __attribute__ ((unused)) = NULL; \
+		__buf = __dummy; \
+	} \
+	(__recsize) ? \
+	__kfifo_out_peek_r(__kfifo, __buf, __n, __recsize) : \
+	__kfifo_out_peek(__kfifo, __buf, __n); \
+}) \
+)
+
+extern int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
+	size_t esize, gfp_t gfp_mask);
+
+extern void __kfifo_free(struct __kfifo *fifo);
+
+extern int __kfifo_init(struct __kfifo *fifo, void *buffer,
+	unsigned int size, size_t esize);
+
+extern unsigned int __kfifo_in(struct __kfifo *fifo,
+	const void *buf, unsigned int len);
+
+extern unsigned int __kfifo_out(struct __kfifo *fifo,
+	void *buf, unsigned int len);
+
+extern int __kfifo_from_user(struct __kfifo *fifo,
+	const void __user *from, unsigned long len, unsigned int *copied);
+
+extern int __kfifo_to_user(struct __kfifo *fifo,
+	void __user *to, unsigned long len, unsigned int *copied);
+
+extern unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
+	struct scatterlist *sgl, int nents, unsigned int len);
+
+extern unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
+	struct scatterlist *sgl, int nents, unsigned int len);
+
+extern unsigned int __kfifo_out_peek(struct __kfifo *fifo,
+	void *buf, unsigned int len);
+
+extern unsigned int __kfifo_in_r(struct __kfifo *fifo,
+	const void *buf, unsigned int len, size_t recsize);
+
+extern unsigned int __kfifo_out_r(struct __kfifo *fifo,
+	void *buf, unsigned int len, size_t recsize);
+
+extern int __kfifo_from_user_r(struct __kfifo *fifo,
+	const void __user *from, unsigned long len, unsigned int *copied,
+	size_t recsize);
+
+extern int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
+	unsigned long len, unsigned int *copied, size_t recsize);
+
+extern unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
+	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize);
+
+extern void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
+	unsigned int len, size_t recsize);
+
+extern unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
+	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize);
+
+extern void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize);
+
+extern unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize);
+
+extern unsigned int __kfifo_out_peek_r(struct __kfifo *fifo,
+	void *buf, unsigned int len, size_t recsize);
+
+extern unsigned int __kfifo_max_r(unsigned int len, size_t recsize);
+
+#endif
diff --git a/kernel/kfifo-new.c b/kernel/kfifo-new.c
new file mode 100644
index 0000000..02192dd
--- /dev/null
+++ b/kernel/kfifo-new.c
@@ -0,0 +1,602 @@
+/*
+ * A generic kernel FIFO implementation
+ *
+ * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/log2.h>
+#include <linux/uaccess.h>
+#include <linux/kfifo.h>
+
+/*
+ * internal helper to calculate the unused elements in a fifo
+ */
+static inline unsigned int kfifo_unused(struct __kfifo *fifo)
+{
+	return (fifo->mask + 1) - (fifo->in - fifo->out);
+}
+
+int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
+		size_t esize, gfp_t gfp_mask)
+{
+	/*
+	 * round down to the next power of 2, since our 'let the indices
+	 * wrap' technique works only in this case.
+	 */
+	if (!is_power_of_2(size))
+		size = rounddown_pow_of_two(size);
+
+	fifo->in = 0;
+	fifo->out = 0;
+	fifo->esize = esize;
+
+	if (size < 2) {
+		fifo->data = NULL;
+		fifo->mask = 0;
+		return -EINVAL;
+	}
+
+	fifo->data = kmalloc(size * esize, gfp_mask);
+
+	if (!fifo->data) {
+		fifo->mask = 0;
+		return -ENOMEM;
+	}
+	fifo->mask = size - 1;
+
+	return 0;
+}
+EXPORT_SYMBOL(__kfifo_alloc);
+
+void __kfifo_free(struct __kfifo *fifo)
+{
+	kfree(fifo->data);
+	fifo->in = 0;
+	fifo->out = 0;
+	fifo->esize = 0;
+	fifo->data = NULL;
+	fifo->mask = 0;
+}
+EXPORT_SYMBOL(__kfifo_free);
+
+int __kfifo_init(struct __kfifo *fifo, void *buffer,
+		unsigned int size, size_t esize)
+{
+	size /= esize;
+
+	if (!is_power_of_2(size))
+		size = rounddown_pow_of_two(size);
+
+	fifo->in = 0;
+	fifo->out = 0;
+	fifo->esize = esize;
+	fifo->data = buffer;
+
+	if (size < 2) {
+		fifo->mask = 0;
+		return -EINVAL;
+	}
+	fifo->mask = size - 1;
+
+	return 0;
+}
+EXPORT_SYMBOL(__kfifo_init);
+
+static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
+		unsigned int len, unsigned int off)
+{
+	unsigned int size = fifo->mask + 1;
+	unsigned int esize = fifo->esize;
+	unsigned int l;
+
+	off &= fifo->mask;
+	if (esize != 1) {
+		off *= esize;
+		size *= esize;
+		len *= esize;
+	}
+	l = min(len, size - off);
+
+	memcpy(fifo->data + off, src, l);
+	memcpy(fifo->data, src + l, len - l);
+	/*
+	 * make sure that the data in the fifo is up to date before
+	 * incrementing the fifo->in index counter
+	 */
+	smp_wmb();
+}
+
+unsigned int __kfifo_in(struct __kfifo *fifo,
+		const void *buf, unsigned int len)
+{
+	unsigned int l;
+
+	l = kfifo_unused(fifo);
+	if (len > l)
+		len = l;
+
+	kfifo_copy_in(fifo, buf, len, fifo->in);
+	fifo->in += len;
+	return len;
+}
+EXPORT_SYMBOL(__kfifo_in);
+
+static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
+		unsigned int len, unsigned int off)
+{
+	unsigned int size = fifo->mask + 1;
+	unsigned int esize = fifo->esize;
+	unsigned int l;
+
+	off &= fifo->mask;
+	if (esize != 1) {
+		off *= esize;
+		size *= esize;
+		len *= esize;
+	}
+	l = min(len, size - off);
+
+	memcpy(dst, fifo->data + off, l);
+	memcpy(dst + l, fifo->data, len - l);
+	/*
+	 * make sure that the data is copied before
+	 * incrementing the fifo->out index counter
+	 */
+	smp_wmb();
+}
+
+unsigned int __kfifo_out_peek(struct __kfifo *fifo,
+		void *buf, unsigned int len)
+{
+	unsigned int l;
+
+	l = fifo->in - fifo->out;
+	if (len > l)
+		len = l;
+
+	kfifo_copy_out(fifo, buf, len, fifo->out);
+	return len;
+}
+EXPORT_SYMBOL(__kfifo_out_peek);
+
+unsigned int __kfifo_out(struct __kfifo *fifo,
+		void *buf, unsigned int len)
+{
+	len = __kfifo_out_peek(fifo, buf, len);
+	fifo->out += len;
+	return len;
+}
+EXPORT_SYMBOL(__kfifo_out);
+
+static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
+	const void __user *from, unsigned int len, unsigned int off,
+	unsigned int *copied)
+{
+	unsigned int size = fifo->mask + 1;
+	unsigned int esize = fifo->esize;
+	unsigned int l;
+	unsigned long ret;
+
+	off &= fifo->mask;
+	if (esize != 1) {
+		off *= esize;
+		size *= esize;
+		len *= esize;
+	}
+	l = min(len, size - off);
+
+	ret = copy_from_user(fifo->data + off, from, l);
+	if (unlikely(ret))
+		ret = DIV_ROUND_UP(ret + len - l, esize);
+	else {
+		ret = copy_from_user(fifo->data, from + l, len - l);
+		if (unlikely(ret))
+			ret = DIV_ROUND_UP(ret, esize);
+	}
+	/*
+	 * make sure that the data in the fifo is up to date before
+	 * incrementing the fifo->in index counter
+	 */
+	smp_wmb();
+	*copied = len - ret;
+	/* return the number of elements which are not copied */
+	return ret;
+}
+
+int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
+		unsigned long len, unsigned int *copied)
+{
+	unsigned int l;
+	unsigned long ret;
+	unsigned int esize = fifo->esize;
+	int err;
+
+	if (esize != 1)
+		len /= esize;
+
+	l = kfifo_unused(fifo);
+	if (len > l)
+		len = l;
+
+	ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
+	if (unlikely(ret)) {
+		len -= ret;
+		err = -EFAULT;
+	} else
+		err = 0;
+	fifo->in += len;
+	return err;
+}
+EXPORT_SYMBOL(__kfifo_from_user);
+
+static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
+		unsigned int len, unsigned int off, unsigned int *copied)
+{
+	unsigned int l;
+	unsigned long ret;
+	unsigned int size = fifo->mask + 1;
+	unsigned int esize = fifo->esize;
+
+	off &= fifo->mask;
+	if (esize != 1) {
+		off *= esize;
+		size *= esize;
+		len *= esize;
+	}
+	l = min(len, size - off);
+
+	ret = copy_to_user(to, fifo->data + off, l);
+	if (unlikely(ret))
+		ret = DIV_ROUND_UP(ret + len - l, esize);
+	else {
+		ret = copy_to_user(to + l, fifo->data, len - l);
+		if (unlikely(ret))
+			ret = DIV_ROUND_UP(ret, esize);
+	}
+	/*
+	 * make sure that the data is copied before
+	 * incrementing the fifo->out index counter
+	 */
+	smp_wmb();
+	*copied = len - ret;
+	/* return the number of elements which are not copied */
+	return ret;
+}
+
+int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
+		unsigned long len, unsigned int *copied)
+{
+	unsigned int l;
+	unsigned long ret;
+	unsigned int esize = fifo->esize;
+	int err;
+
+	if (esize != 1)
+		len /= esize;
+
+	l = fifo->in - fifo->out;
+	if (len > l)
+		len = l;
+	ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
+	if (unlikely(ret)) {
+		len -= ret;
+		err = -EFAULT;
+	} else
+		err = 0;
+	fifo->out += len;
+	return err;
+}
+EXPORT_SYMBOL(__kfifo_to_user);
+
+static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
+		int nents, unsigned int len)
+{
+	int n;
+	unsigned int l;
+	unsigned int off;
+	struct page *page;
+
+	if (!nents)
+		return 0;
+
+	if (!len)
+		return 0;
+
+	n = 0;
+	page = virt_to_page(buf);
+	off = offset_in_page(buf);
+	l = 0;
+
+	while (len >= l + PAGE_SIZE - off) {
+		struct page *npage;
+
+		l += PAGE_SIZE;
+		buf += PAGE_SIZE;
+		npage = virt_to_page(buf);
+		if (page_to_phys(page) != page_to_phys(npage) - l) {
+			sgl->page_link = 0;
+			sg_set_page(sgl++, page, l - off, off);
+			if (++n == nents)
+				return n;
+			page = npage;
+			len -= l - off;
+			l = off = 0;
+		}
+	}
+	sgl->page_link = 0;
+	sg_set_page(sgl++, page, len, off);
+	return n + 1;
+}
+
+static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
+		int nents, unsigned int len, unsigned int off)
+{
+	unsigned int size = fifo->mask + 1;
+	unsigned int esize = fifo->esize;
+	unsigned int l;
+	unsigned int n;
+
+	off &= fifo->mask;
+	if (esize != 1) {
+		off *= esize;
+		size *= esize;
+		len *= esize;
+	}
+	l = min(len, size - off);
+
+	n  = setup_sgl_buf(sgl, fifo->data + off, nents, l);
+	n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
+
+	if (n)
+		sg_mark_end(sgl + n - 1);
+	return n;
+}
+
+unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
+		struct scatterlist *sgl, int nents, unsigned int len)
+{
+	unsigned int l;
+
+	l = kfifo_unused(fifo);
+	if (len > l)
+		len = l;
+
+	return setup_sgl(fifo, sgl, nents, len, fifo->in);
+}
+EXPORT_SYMBOL(__kfifo_dma_in_prepare);
+
+unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
+		struct scatterlist *sgl, int nents, unsigned int len)
+{
+	unsigned int l;
+
+	l = fifo->in - fifo->out;
+	if (len > l)
+		len = l;
+
+	return setup_sgl(fifo, sgl, nents, len, fifo->out);
+}
+EXPORT_SYMBOL(__kfifo_dma_out_prepare);
+
+unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
+{
+	unsigned int max = (1 << (recsize << 3)) - 1;
+
+	if (len > max)
+		return max;
+	return len;
+}
+
+#define	__KFIFO_PEEK(data, out, mask) \
+	((data)[(out) & (mask)])
+/*
+ * __kfifo_peek_n internal helper function for determinate the length of
+ * the next record in the fifo
+ */
+static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
+{
+	unsigned int l;
+	unsigned int mask = fifo->mask;
+	unsigned char *data = fifo->data;
+
+	l = __KFIFO_PEEK(data, fifo->out, mask);
+
+	if (--recsize)
+		l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
+
+	return l;
+}
+
+#define	__KFIFO_POKE(data, in, mask, val) \
+	( \
+	(data)[(in) & (mask)] = (unsigned char)(val) \
+	)
+
+/*
+ * __kfifo_poke_n internal helper function for storeing the length of
+ * the record into the fifo
+ */
+static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
+{
+	unsigned int mask = fifo->mask;
+	unsigned char *data = fifo->data;
+
+	__KFIFO_POKE(data, fifo->in, mask, n);
+
+	if (recsize > 1)
+		__KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
+}
+
+unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
+{
+	return __kfifo_peek_n(fifo, recsize);
+}
+EXPORT_SYMBOL(__kfifo_len_r);
+
+unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
+		unsigned int len, size_t recsize)
+{
+	if (len + recsize > kfifo_unused(fifo))
+		return 0;
+
+	__kfifo_poke_n(fifo, len, recsize);
+
+	kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
+	fifo->in += len + recsize;
+	return len;
+}
+EXPORT_SYMBOL(__kfifo_in_r);
+
+static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
+	void *buf, unsigned int len, size_t recsize, unsigned int *n)
+{
+	*n = __kfifo_peek_n(fifo, recsize);
+
+	if (len > *n)
+		len = *n;
+
+	kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
+	return len;
+}
+
+unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
+		unsigned int len, size_t recsize)
+{
+	unsigned int n;
+
+	if (fifo->in == fifo->out)
+		return 0;
+
+	return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
+}
+EXPORT_SYMBOL(__kfifo_out_peek_r);
+
+unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
+		unsigned int len, size_t recsize)
+{
+	unsigned int n;
+
+	if (fifo->in == fifo->out)
+		return 0;
+
+	len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
+	fifo->out += n + recsize;
+	return len;
+}
+EXPORT_SYMBOL(__kfifo_out_r);
+
+int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
+	unsigned long len, unsigned int *copied, size_t recsize)
+{
+	unsigned long ret;
+
+	len = __kfifo_max_r(len, recsize);
+
+	if (len + recsize > kfifo_unused(fifo)) {
+		*copied = 0;
+		return 0;
+	}
+
+	__kfifo_poke_n(fifo, len, recsize);
+
+	ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
+	if (unlikely(ret)) {
+		*copied = 0;
+		return -EFAULT;
+	}
+	fifo->in += len + recsize;
+	return 0;
+}
+EXPORT_SYMBOL(__kfifo_from_user_r);
+
+int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
+	unsigned long len, unsigned int *copied, size_t recsize)
+{
+	unsigned long ret;
+	unsigned int n;
+
+	if (fifo->in == fifo->out) {
+		*copied = 0;
+		return 0;
+	}
+
+	n = __kfifo_peek_n(fifo, recsize);
+	if (len > n)
+		len = n;
+
+	ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
+	if (unlikely(ret)) {
+		*copied = 0;
+		return -EFAULT;
+	}
+	fifo->out += n + recsize;
+	return 0;
+}
+EXPORT_SYMBOL(__kfifo_to_user_r);
+
+unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
+	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
+{
+	if (!nents)
+		BUG();
+
+	len = __kfifo_max_r(len, recsize);
+
+	if (len + recsize > kfifo_unused(fifo))
+		return 0;
+
+	return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
+}
+EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
+
+void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
+	unsigned int len, size_t recsize)
+{
+	len = __kfifo_max_r(len, recsize);
+	__kfifo_poke_n(fifo, len, recsize);
+	fifo->in += len + recsize;
+}
+EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
+
+unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
+	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
+{
+	if (!nents)
+		BUG();
+
+	len = __kfifo_max_r(len, recsize);
+
+	if (len + recsize > fifo->in - fifo->out)
+		return 0;
+
+	return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
+}
+EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
+
+void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
+{
+	unsigned int len;
+
+	len = __kfifo_peek_n(fifo, recsize);
+	fifo->out += len + recsize;
+}
+EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
-- 
1.7.0.4

[PATCH 3/4] replace the old non generic API

[stefani]

From: Stefani Seibold <stefani@seibold.net>

This patch simple replace the whole kfifo.c and kfifo.h files by the new
generic version and fix the kerneldoc API template file.

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
 Documentation/DocBook/kernel-api.tmpl  |    1 -
 include/linux/{kfifo-new.h => kfifo.h} |    0
 kernel/{kfifo-new.c => kfifo.c}        |    0
 3 files changed, 0 insertions(+), 1 deletions(-)
 rename include/linux/{kfifo-new.h => kfifo.h} (100%)
 rename kernel/{kfifo-new.c => kfifo.c} (100%)

diff --git a/Documentation/DocBook/kernel-api.tmpl b/Documentation/DocBook/kernel-api.tmpl
index 44b3def..a20c6f6 100644
--- a/Documentation/DocBook/kernel-api.tmpl
+++ b/Documentation/DocBook/kernel-api.tmpl
@@ -132,7 +132,6 @@ X!Ilib/string.c
      <title>FIFO Buffer</title>
      <sect1><title>kfifo interface</title>
 !Iinclude/linux/kfifo.h
-!Ekernel/kfifo.c
      </sect1>
   </chapter>
 
diff --git a/include/linux/kfifo-new.h b/include/linux/kfifo.h
similarity index 100%
rename from include/linux/kfifo-new.h
rename to include/linux/kfifo.h
diff --git a/kernel/kfifo-new.c b/kernel/kfifo.c
similarity index 100%
rename from kernel/kfifo-new.c
rename to kernel/kfifo.c
-- 
1.7.0.4

[PATCH 4/4] add example files to the kernel sample directory

[stefani]

From: Stefani Seibold <stefani@seibold.net>

This patch add four examples to the kernel sample directory.

It shows how to handle:
- a byte stream fifo
- a integer type fifo
- a dynamic record sized fifo
- the fifo DMA functions

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
 samples/Kconfig                    |   10 ++
 samples/Makefile                   |    2 +-
 samples/kfifo/Makefile             |    1 +
 samples/kfifo/bytestream-example.c |  163 +++++++++++++++++++++++++++++++++++
 samples/kfifo/dma-example.c        |  115 +++++++++++++++++++++++++
 samples/kfifo/inttype-example.c    |  157 +++++++++++++++++++++++++++++++++
 samples/kfifo/record-example.c     |  167 ++++++++++++++++++++++++++++++++++++
 7 files changed, 614 insertions(+), 1 deletions(-)
 create mode 100644 samples/kfifo/Makefile
 create mode 100644 samples/kfifo/bytestream-example.c
 create mode 100644 samples/kfifo/dma-example.c
 create mode 100644 samples/kfifo/inttype-example.c
 create mode 100644 samples/kfifo/record-example.c

diff --git a/samples/Kconfig b/samples/Kconfig
index 8924f72..954a1d5 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -44,4 +44,14 @@ config SAMPLE_HW_BREAKPOINT
 	help
 	  This builds kernel hardware breakpoint example modules.
 
+config SAMPLE_KFIFO
+	tristate "Build kfifo examples -- loadable modules only"
+	depends on m
+	help
+	  This config option will allow you to build a number of
+	  different kfifo sample modules showing how to use the
+	  generic kfifo API.
+
+	  If in doubt, say "N" here.
+
 endif # SAMPLES
diff --git a/samples/Makefile b/samples/Makefile
index 0f15e6d..76b3c34 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,4 +1,4 @@
 # Makefile for Linux samples code
 
 obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ tracepoints/ trace_events/ \
-			   hw_breakpoint/
+			   hw_breakpoint/ kfifo/
diff --git a/samples/kfifo/Makefile b/samples/kfifo/Makefile
new file mode 100644
index 0000000..bcc9484
--- /dev/null
+++ b/samples/kfifo/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SAMPLE_KFIFO) += bytestream-example.o dma-example.o inttype-example.o record-example.o
diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c
new file mode 100644
index 0000000..642eef3
--- /dev/null
+++ b/samples/kfifo/bytestream-example.c
@@ -0,0 +1,163 @@
+/*
+ * Sample kfifo byte stream implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a byte stream fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"bytestream-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static struct kfifo test;
+#else
+static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	unsigned char	buf[6];
+	unsigned char	i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "byte stream fifo test start\n");
+
+	/* put string into the fifo */
+	kfifo_in(&test, "hello", 5);
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 5 bytes from the fifo */
+	i = kfifo_out(&test, buf, 5);
+	printk(KERN_INFO "buf: %.*s\n", i, buf);
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	/* put values into the fifo until is full */
+	for (i = 20; kfifo_put(&test, &i); i++)
+		;
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
new file mode 100644
index 0000000..4ef4749
--- /dev/null
+++ b/samples/kfifo/dma-example.c
@@ -0,0 +1,115 @@
+/*
+ * Sample fifo dma implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to handle fifo dma operations.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+static struct kfifo fifo;
+
+static int __init example_init(void)
+{
+	int 			i;
+	unsigned int 		ret;
+	struct scatterlist	sg[10];
+
+	printk(KERN_INFO "DMA fifo test start\n");
+
+	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return 1;
+	}
+
+	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
+
+	kfifo_in(&fifo, "test", 4);
+
+	for (i = 0; i != 9; i++)
+		kfifo_put(&fifo, &i);
+
+	/* kick away first byte */
+	ret = kfifo_get(&fifo, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, fifo is full and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for receive:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: zero bytes received */
+		ret = 0;
+
+		/* finish the dma operation and update the received data */
+		kfifo_dma_in_finish(&fifo, ret);
+	}
+
+	ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, no data was available and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for transmit:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: 5 bytes transmitted */
+		ret = 5;
+
+		/* finish the dma operation and update the transmitted data */
+		kfifo_dma_out_finish(&fifo, ret);
+	}
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c
new file mode 100644
index 0000000..d6c5b7d
--- /dev/null
+++ b/samples/kfifo/inttype-example.c
@@ -0,0 +1,157 @@
+/*
+ * Sample kfifo int type implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a int type fifo.
+ */
+
+/* fifo size in elements (ints) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"int-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static DECLARE_KFIFO_PTR(test, int);
+#else
+static DEFINE_KFIFO(test, int, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	int		buf[6];
+	int		i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "int fifo test start\n");
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	for (i = 20; i != 30; i++)
+		kfifo_put(&test, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* show the first value without removing from the fifo */
+	if (kfifo_peek(&test, &i))
+		printk(KERN_INFO "%d\n", i);
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c
new file mode 100644
index 0000000..32c6e0b
--- /dev/null
+++ b/samples/kfifo/record-example.c
@@ -0,0 +1,167 @@
+/*
+ * Sample dynamic sized record fifo implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a variable sized record fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	128
+
+/* name of the proc entry */
+#define	PROC_FIFO	"record-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+/*
+ * struct kfifo_rec_ptr_1 and  STRUCT_KFIFO_REC_1 can handle records of a
+ * length between 0 and 255 bytes.
+ *
+ * struct kfifo_rec_ptr_2 and  STRUCT_KFIFO_REC_2 can handle records of a
+ * length between 0 and 65535 bytes.
+ */
+
+#ifdef DYNAMIC
+struct kfifo_rec_ptr_1 test;
+
+#else
+typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
+
+static mytest test;
+#endif
+
+static int __init testfunc(void)
+{
+	char		buf[100];
+	unsigned int	i;
+	unsigned int	ret;
+	struct { unsigned char buf[6]; } hello = { "hello" };
+
+	printk(KERN_INFO "record fifo test start\n");
+
+	kfifo_in(&test, &hello, sizeof(hello));
+
+	/* show the size of the next record in the fifo */
+	printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test));
+
+	/* put in variable length data */
+	for (i = 0; i < 10; i++) {
+		memset(buf, 'a' + i, i + 1);
+		kfifo_in(&test, buf, i + 1);
+	}
+
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* show the first record without removing from the fifo */
+	ret = kfifo_out_peek(&test, buf, sizeof(buf));
+	if (ret)
+		printk(KERN_INFO "%.*s\n", ret, buf);
+
+	/* print out all records in the fifo */
+	while (!kfifo_is_empty(&test)) {
+		ret = kfifo_out(&test, buf, sizeof(buf));
+		printk(KERN_INFO "%.*s\n", ret, buf);
+	}
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
-- 
1.7.0.4

Re: [PATCH 4/4] add example files to the kernel sample directory

[Andrew Morton]

On Wed, 12 May 2010 10:49:27 +0200
stefani@seibold.net wrote:

> This patch add four examples to the kernel sample directory.

x86_64 allmodconfig:

samples/kfifo/dma-example.c: In function 'example_init':
samples/kfifo/dma-example.c:27: error: array type has incomplete element type
samples/kfifo/dma-example.c:41: error: implicit declaration of function 'kfifo_put'
samples/kfifo/dma-example.c:44: error: implicit declaration of function 'kfifo_get'
samples/kfifo/dma-example.c:48: error: implicit declaration of function 'kfifo_dma_in_prepare'
samples/kfifo/dma-example.c:48: warning: type defaults to 'int' in declaration of 'type name'
samples/kfifo/dma-example.c:48: warning: type defaults to 'int' in declaration of 'type name'
samples/kfifo/dma-example.c:48: error: negative width in bit-field '<anonymous>'
samples/kfifo/dma-example.c:54: warning: type defaults to 'int' in declaration of 'type name'
samples/kfifo/dma-example.c:54: warning: type defaults to 'int' in declaration of 'type name'
samples/kfifo/dma-example.c:54: error: negative width in bit-field '<anonymous>'
samples/kfifo/dma-example.c:60: error: implicit declaration of function 'sg_is_last'
samples/kfifo/dma-example.c:71: error: implicit declaration of function 'kfifo_dma_in_finish'
samples/kfifo/dma-example.c:74: error: implicit declaration of function 'kfifo_dma_out_prepare'
samples/kfifo/dma-example.c:74: warning: type defaults to 'int' in declaration of 'type name'
samples/kfifo/dma-example.c:74: warning: type defaults to 'int' in declaration of 'type name'
samples/kfifo/dma-example.c:74: error: negative width in bit-field '<anonymous>'
samples/kfifo/dma-example.c:80: warning: type defaults to 'int' in declaration of 'type name'
samples/kfifo/dma-example.c:80: warning: type defaults to 'int' in declaration of 'type name'
samples/kfifo/dma-example.c:80: error: negative width in bit-field '<anonymous>'
samples/kfifo/dma-example.c:97: error: implicit declaration of function 'kfifo_dma_out_finish'
samples/kfifo/dma-example.c:27: warning: unused variable 'sg'
make[2]: *** [samples/kfifo/dma-example.o] Error 1
make[2]: *** Waiting for unfinished jobs....
samples/kfifo/bytestream-example.c:44:52: error: macro "DECLARE_KFIFO" passed 3 arguments, but takes just 2
samples/kfifo/bytestream-example.c:44: warning: type defaults to 'int' in declaration of 'DECLARE_KFIFO'
samples/kfifo/bytestream-example.c: In function 'testfunc':
samples/kfifo/bytestream-example.c:56: error: 'test' undeclared (first use in this function)
samples/kfifo/bytestream-example.c:56: error: (Each undeclared identifier is reported only once
samples/kfifo/bytestream-example.c:56: error: for each function it appears in.)
samples/kfifo/bytestream-example.c:60: error: implicit declaration of function 'kfifo_put'
samples/kfifo/bytestream-example.c:83: error: implicit declaration of function 'kfifo_get'
samples/kfifo/bytestream-example.c: In function 'fifo_write':
samples/kfifo/bytestream-example.c:99: error: 'test' undeclared (first use in this function)
samples/kfifo/bytestream-example.c: In function 'fifo_read':
samples/kfifo/bytestream-example.c:115: error: 'test' undeclared (first use in this function)
samples/kfifo/bytestream-example.c: In function 'example_init':
samples/kfifo/bytestream-example.c:139: error: 'test' undeclared (first use in this function)
samples/kfifo/bytestream-example.c:139: error: 'testkfifo_buffer' undeclared (first use in this function)
make[2]: *** [samples/kfifo/bytestream-example.o] Error 1
samples/kfifo/record-example.c:53: error: syntax error before numeric constant
samples/kfifo/record-example.c:53: warning: type defaults to 'int' in declaration of 'mytest'
samples/kfifo/record-example.c:53: warning: data definition has no type or storage class
samples/kfifo/record-example.c:55: error: syntax error before 'test'
samples/kfifo/record-example.c:55: warning: type defaults to 'int' in declaration of 'test'
samples/kfifo/record-example.c:55: warning: data definition has no type or storage class
samples/kfifo/record-example.c: In function 'testfunc':
samples/kfifo/record-example.c:67: warning: passing argument 1 of 'kfifo_in' from incompatible pointer type
samples/kfifo/record-example.c:70: error: implicit declaration of function 'kfifo_peek_len'
samples/kfifo/record-example.c:75: warning: passing argument 1 of 'kfifo_in' from incompatible pointer type
samples/kfifo/record-example.c:78: warning: passing argument 1 of 'kfifo_len' from incompatible pointer type
samples/kfifo/record-example.c:81: warning: passing argument 1 of 'kfifo_out_peek' from incompatible pointer type
samples/kfifo/record-example.c:81: error: too few arguments to function 'kfifo_out_peek'
samples/kfifo/record-example.c:86: warning: passing argument 1 of 'kfifo_is_empty' from incompatible pointer type
samples/kfifo/record-example.c:87: warning: passing argument 1 of 'kfifo_out' from incompatible pointer type
samples/kfifo/record-example.c: In function 'fifo_write':
samples/kfifo/record-example.c:103: warning: passing argument 1 of 'kfifo_from_user' from incompatible pointer type
samples/kfifo/record-example.c: In function 'fifo_read':
samples/kfifo/record-example.c:119: warning: passing argument 1 of 'kfifo_to_user' from incompatible pointer type
samples/kfifo/record-example.c: In function 'example_init':
samples/kfifo/record-example.c:143: error: 'testkfifo_buffer' undeclared (first use in this function)
samples/kfifo/record-example.c:143: error: (Each undeclared identifier is reported only once
samples/kfifo/record-example.c:143: error: for each function it appears in.)
samples/kfifo/record-example.c:143: error: incompatible types in assignment
make[2]: *** [samples/kfifo/record-example.o] Error 1
samples/kfifo/inttype-example.c:44:41: error: macro "DEFINE_KFIFO" passed 3 arguments, but takes just 2
samples/kfifo/inttype-example.c:44: warning: type defaults to 'int' in declaration of 'DEFINE_KFIFO'
samples/kfifo/inttype-example.c: In function 'testfunc':
samples/kfifo/inttype-example.c:57: error: implicit declaration of function 'kfifo_put'
samples/kfifo/inttype-example.c:57: error: 'test' undeclared (first use in this function)
samples/kfifo/inttype-example.c:57: error: (Each undeclared identifier is reported only once
samples/kfifo/inttype-example.c:57: error: for each function it appears in.)
samples/kfifo/inttype-example.c:75: error: implicit declaration of function 'kfifo_peek'
samples/kfifo/inttype-example.c:79: error: implicit declaration of function 'kfifo_get'
samples/kfifo/inttype-example.c: In function 'fifo_write':
samples/kfifo/inttype-example.c:95: error: 'test' undeclared (first use in this function)
samples/kfifo/inttype-example.c: In function 'fifo_read':
samples/kfifo/inttype-example.c:111: error: 'test' undeclared (first use in this function)

Re: [PATCH 4/4] add example files to the kernel sample directory

[Stefani Seibold]

Hi,

is the patch 0003-replace-the-old-non-generic-API.patch correct applied?

This patch renames the files created by patch 

0002-add-the-new-generic-kfifo-API.patch 

from 
kernel/kfifo-new.c into kernel/kfifo.c
and
include/linux/kfifo-new.h into include/linux/kfifo.h.

Both destination files still exists, so git must overwrite them. This
was done in request by Greg, not to break the kernel build at this point
in the patch sequence.

Stefani

Am Freitag, den 14.05.2010, 13:46 -0700 schrieb Andrew Morton:
> On Wed, 12 May 2010 10:49:27 +0200
> stefani@seibold.net wrote:
> 
> > This patch add four examples to the kernel sample directory.
> 
> x86_64 allmodconfig:
> 
> samples/kfifo/dma-example.c: In function 'example_init':
> samples/kfifo/dma-example.c:27: error: array type has incomplete element type
> samples/kfifo/dma-example.c:41: error: implicit declaration of function 'kfifo_put'
> samples/kfifo/dma-example.c:44: error: implicit declaration of function 'kfifo_get'
> samples/kfifo/dma-example.c:48: error: implicit declaration of function 'kfifo_dma_in_prepare'
> samples/kfifo/dma-example.c:48: warning: type defaults to 'int' in declaration of 'type name'
> samples/kfifo/dma-example.c:48: warning: type defaults to 'int' in declaration of 'type name'
> samples/kfifo/dma-example.c:48: error: negative width in bit-field '<anonymous>'
> samples/kfifo/dma-example.c:54: warning: type defaults to 'int' in declaration of 'type name'
> samples/kfifo/dma-example.c:54: warning: type defaults to 'int' in declaration of 'type name'
> samples/kfifo/dma-example.c:54: error: negative width in bit-field '<anonymous>'
> samples/kfifo/dma-example.c:60: error: implicit declaration of function 'sg_is_last'
> samples/kfifo/dma-example.c:71: error: implicit declaration of function 'kfifo_dma_in_finish'
> samples/kfifo/dma-example.c:74: error: implicit declaration of function 'kfifo_dma_out_prepare'
> samples/kfifo/dma-example.c:74: warning: type defaults to 'int' in declaration of 'type name'
> samples/kfifo/dma-example.c:74: warning: type defaults to 'int' in declaration of 'type name'
> samples/kfifo/dma-example.c:74: error: negative width in bit-field '<anonymous>'
> samples/kfifo/dma-example.c:80: warning: type defaults to 'int' in declaration of 'type name'
> samples/kfifo/dma-example.c:80: warning: type defaults to 'int' in declaration of 'type name'
> samples/kfifo/dma-example.c:80: error: negative width in bit-field '<anonymous>'
> samples/kfifo/dma-example.c:97: error: implicit declaration of function 'kfifo_dma_out_finish'
> samples/kfifo/dma-example.c:27: warning: unused variable 'sg'
> make[2]: *** [samples/kfifo/dma-example.o] Error 1
> make[2]: *** Waiting for unfinished jobs....
> samples/kfifo/bytestream-example.c:44:52: error: macro "DECLARE_KFIFO" passed 3 arguments, but takes just 2
> samples/kfifo/bytestream-example.c:44: warning: type defaults to 'int' in declaration of 'DECLARE_KFIFO'
> samples/kfifo/bytestream-example.c: In function 'testfunc':
> samples/kfifo/bytestream-example.c:56: error: 'test' undeclared (first use in this function)
> samples/kfifo/bytestream-example.c:56: error: (Each undeclared identifier is reported only once
> samples/kfifo/bytestream-example.c:56: error: for each function it appears in.)
> samples/kfifo/bytestream-example.c:60: error: implicit declaration of function 'kfifo_put'
> samples/kfifo/bytestream-example.c:83: error: implicit declaration of function 'kfifo_get'
> samples/kfifo/bytestream-example.c: In function 'fifo_write':
> samples/kfifo/bytestream-example.c:99: error: 'test' undeclared (first use in this function)
> samples/kfifo/bytestream-example.c: In function 'fifo_read':
> samples/kfifo/bytestream-example.c:115: error: 'test' undeclared (first use in this function)
> samples/kfifo/bytestream-example.c: In function 'example_init':
> samples/kfifo/bytestream-example.c:139: error: 'test' undeclared (first use in this function)
> samples/kfifo/bytestream-example.c:139: error: 'testkfifo_buffer' undeclared (first use in this function)
> make[2]: *** [samples/kfifo/bytestream-example.o] Error 1
> samples/kfifo/record-example.c:53: error: syntax error before numeric constant
> samples/kfifo/record-example.c:53: warning: type defaults to 'int' in declaration of 'mytest'
> samples/kfifo/record-example.c:53: warning: data definition has no type or storage class
> samples/kfifo/record-example.c:55: error: syntax error before 'test'
> samples/kfifo/record-example.c:55: warning: type defaults to 'int' in declaration of 'test'
> samples/kfifo/record-example.c:55: warning: data definition has no type or storage class
> samples/kfifo/record-example.c: In function 'testfunc':
> samples/kfifo/record-example.c:67: warning: passing argument 1 of 'kfifo_in' from incompatible pointer type
> samples/kfifo/record-example.c:70: error: implicit declaration of function 'kfifo_peek_len'
> samples/kfifo/record-example.c:75: warning: passing argument 1 of 'kfifo_in' from incompatible pointer type
> samples/kfifo/record-example.c:78: warning: passing argument 1 of 'kfifo_len' from incompatible pointer type
> samples/kfifo/record-example.c:81: warning: passing argument 1 of 'kfifo_out_peek' from incompatible pointer type
> samples/kfifo/record-example.c:81: error: too few arguments to function 'kfifo_out_peek'
> samples/kfifo/record-example.c:86: warning: passing argument 1 of 'kfifo_is_empty' from incompatible pointer type
> samples/kfifo/record-example.c:87: warning: passing argument 1 of 'kfifo_out' from incompatible pointer type
> samples/kfifo/record-example.c: In function 'fifo_write':
> samples/kfifo/record-example.c:103: warning: passing argument 1 of 'kfifo_from_user' from incompatible pointer type
> samples/kfifo/record-example.c: In function 'fifo_read':
> samples/kfifo/record-example.c:119: warning: passing argument 1 of 'kfifo_to_user' from incompatible pointer type
> samples/kfifo/record-example.c: In function 'example_init':
> samples/kfifo/record-example.c:143: error: 'testkfifo_buffer' undeclared (first use in this function)
> samples/kfifo/record-example.c:143: error: (Each undeclared identifier is reported only once
> samples/kfifo/record-example.c:143: error: for each function it appears in.)
> samples/kfifo/record-example.c:143: error: incompatible types in assignment
> make[2]: *** [samples/kfifo/record-example.o] Error 1
> samples/kfifo/inttype-example.c:44:41: error: macro "DEFINE_KFIFO" passed 3 arguments, but takes just 2
> samples/kfifo/inttype-example.c:44: warning: type defaults to 'int' in declaration of 'DEFINE_KFIFO'
> samples/kfifo/inttype-example.c: In function 'testfunc':
> samples/kfifo/inttype-example.c:57: error: implicit declaration of function 'kfifo_put'
> samples/kfifo/inttype-example.c:57: error: 'test' undeclared (first use in this function)
> samples/kfifo/inttype-example.c:57: error: (Each undeclared identifier is reported only once
> samples/kfifo/inttype-example.c:57: error: for each function it appears in.)
> samples/kfifo/inttype-example.c:75: error: implicit declaration of function 'kfifo_peek'
> samples/kfifo/inttype-example.c:79: error: implicit declaration of function 'kfifo_get'
> samples/kfifo/inttype-example.c: In function 'fifo_write':
> samples/kfifo/inttype-example.c:95: error: 'test' undeclared (first use in this function)
> samples/kfifo/inttype-example.c: In function 'fifo_read':
> samples/kfifo/inttype-example.c:111: error: 'test' undeclared (first use in this function)
> 

Re: [PATCH 4/4] add example files to the kernel sample directory

[Andrew Morton]

On Sat, 15 May 2010 15:33:38 +0200 Stefani Seibold <stefani@seibold.net> wrote:

> Hi,
> 
> is the patch 0003-replace-the-old-non-generic-API.patch correct applied?
> 
> This patch renames the files created by patch 
> 
> 0002-add-the-new-generic-kfifo-API.patch 
> 
> from 
> kernel/kfifo-new.c into kernel/kfifo.c
> and
> include/linux/kfifo-new.h into include/linux/kfifo.h.
> 
> Both destination files still exists, so git must overwrite them.

oh, doh, no.  This stuff:

: diff --git a/include/linux/kfifo-new.h b/include/linux/kfifo.h
: similarity index 100%
: rename from include/linux/kfifo-new.h
: rename to include/linux/kfifo.h
: diff --git a/kernel/kfifo-new.c b/kernel/kfifo.c
: similarity index 100%
: rename from kernel/kfifo-new.c
: rename to kernel/kfifo.c

is git-specific and doesn't mean anything to patch(1).  I'll fix it.

> This
> was done in request by Greg, not to break the kernel build at this point
> in the patch sequence.

Well, there can be no build problem here (joining two
non-build-breaking patches will yield a non-build-breaking patch!) but
if the add-new-api and replace-old-api patches were folded into a
single patch, the diff would be quite unreadable.

Re: really generic, type save and type definable.

[Henrik Rydberg]

stefani@seibold.net wrote:
[...]
> The main goal was to provide an API which is very intuitive, save and easy
> to use. So linux will get now a powerful fifo API which provides all what 
> a developer needs. This will save in the future a lot of kernel space, since
> there is no need to write an own implementation. Most of the device driver 
> developers need a fifo, and also deep kernel development will gain benefit 
> from this API.

The meaning of the term "multiple readers" referred to in the header is somewhat
ambiguous. It could in principle refer to concurrent reading of the same
position, or concurrent reading from different positions. Imaginably, those
cases also have different locking behavior.

What happens if two fifos are initialized with the same memory buffer?

What about one-to-many and many-to-one cases? The input system and the logging
facilities could serve as examples where such buffers would be useful.

Henrik

Re: really generic, type save and type definable.

[Stefani Seibold]

Am Freitag, den 28.05.2010, 09:43 +0200 schrieb Henrik Rydberg:
> stefani@seibold.net wrote:
> [...]
> > The main goal was to provide an API which is very intuitive, save and easy
> > to use. So linux will get now a powerful fifo API which provides all what 
> > a developer needs. This will save in the future a lot of kernel space, since
> > there is no need to write an own implementation. Most of the device driver 
> > developers need a fifo, and also deep kernel development will gain benefit 
> > from this API.
> 
> The meaning of the term "multiple readers" referred to in the header is somewhat
> ambiguous. It could in principle refer to concurrent reading of the same
> position, or concurrent reading from different positions. Imaginably, those
> cases also have different locking behavior.
> 
> What happens if two fifos are initialized with the same memory buffer?
> 

That would be a big nonsense! Tell me a real use case for such kind of
request...

> What about one-to-many and many-to-one cases? The input system and the logging
> facilities could serve as examples where such buffers would be useful.
> 

There is no ne-to-many and many-to-one cases since the API will handle
this. You can not read more data then fit in the fifo, also u can not
write more data the fifo can handle.

Stefani

Re: really generic, type save and type definable.

[Henrik Rydberg]

Stefani Seibold wrote:
> Am Freitag, den 28.05.2010, 09:43 +0200 schrieb Henrik Rydberg:
>> stefani@seibold.net wrote:
>> [...]
>>> The main goal was to provide an API which is very intuitive, save and easy
>>> to use. So linux will get now a powerful fifo API which provides all what 
>>> a developer needs. This will save in the future a lot of kernel space, since
>>> there is no need to write an own implementation. Most of the device driver 
>>> developers need a fifo, and also deep kernel development will gain benefit 
>>> from this API.
>> The meaning of the term "multiple readers" referred to in the header is somewhat
>> ambiguous. It could in principle refer to concurrent reading of the same
>> position, or concurrent reading from different positions. Imaginably, those
>> cases also have different locking behavior.
>>
>> What happens if two fifos are initialized with the same memory buffer?
>>
> 
> That would be a big nonsense! Tell me a real use case for such kind of
> request...

I am referring to a buffer where one thread writes data to the queue, and
several other threads read the _same_ data from the queue. Such a queue would
most likely have separate storage for the (buffer, head) on one hand, and the
tails on the other hand. I was interested in whether anyone had put any thought
into it, in particular with regard to a possible lock-less implementation.

I understand that it is not a good idea to use the same memory buffer in your
kfifo implementation, I was merely suggesting the documentation say so as well.

> 
>> What about one-to-many and many-to-one cases? The input system and the logging
>> facilities could serve as examples where such buffers would be useful.
>>
> 
> There is no ne-to-many and many-to-one cases since the API will handle
> this. You can not read more data then fit in the fifo, also u can not
> write more data the fifo can handle.

I am not sure is this comment means "the API will not allow it", or if we simply
got off on the wrong foot. If there is no interest in a one-to-many buffer, all
is fine. Otherwise, this thread seems like an appropriate place for such a
discussion, does it not?

Henrik

Re: [PATCH 2/4] add the new generic kfifo API

[Ira W. Snyder]

On Wed, May 12, 2010 at 10:49:25AM +0200, stefani@seibold.net wrote:
> From: Stefani Seibold <stefani@seibold.net>
> 
> add the new version of the kfifo API files kfifo.c and kfifo.h.
> 
> Signed-off-by: Stefani Seibold <stefani@seibold.net>
> ---
>  include/linux/kfifo-new.h |  844 +++++++++++++++++++++++++++++++++++++++++++++
>  kernel/kfifo-new.c        |  602 ++++++++++++++++++++++++++++++++
>  2 files changed, 1446 insertions(+), 0 deletions(-)
>  create mode 100644 include/linux/kfifo-new.h
>  create mode 100644 kernel/kfifo-new.c
> 
> diff --git a/include/linux/kfifo-new.h b/include/linux/kfifo-new.h
> new file mode 100644
> index 0000000..311f875
> --- /dev/null
> +++ b/include/linux/kfifo-new.h
> @@ -0,0 +1,844 @@
> +/*
> + * A generic kernel FIFO implementation
> + *
> + * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> + *
> + */
> +
> +#ifndef _LINUX_KFIFO_H
> +#define _LINUX_KFIFO_H
> +
> +/*
> + * How to porting drivers to the new generic FIFO API:
> + *
> + * - Modify the declaration of the "struct kfifo *" object into a
> + *   in-place "struct kfifo" object
> + * - Init the in-place object with kfifo_alloc() or kfifo_init()
> + *   Note: The address of the in-place "struct kfifo" object must be
> + *   passed as the first argument to this functions
> + * - Replace the use of __kfifo_put into kfifo_in and __kfifo_get
> + *   into kfifo_out
> + * - Replace the use of kfifo_put into kfifo_in_spinlocked and kfifo_get
> + *   into kfifo_out_spinlocked
> + *   Note: the spinlock pointer formerly passed to kfifo_init/kfifo_alloc
> + *   must be passed now to the kfifo_in_spinlocked and kfifo_out_spinlocked
> + *   as the last parameter
> + * - The formerly __kfifo_* functions are renamed into kfifo_*
> + */
> +
> +/*
> + * Note about locking : There is no locking required until only * one reader
> + * and one writer is using the fifo and no kfifo_reset() will be * called
> + *  kfifo_reset_out() can be safely used, until it will be only called
> + * in the reader thread.
> + *  For multiple writer and one reader there is only a need to lock the writer.
> + * And vice versa for only one writer and multiple reader there is only a need
> + * to lock the reader.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/spinlock.h>
> +#include <linux/stddef.h>
> +#include <linux/scatterlist.h>
> +
> +struct __kfifo {
> +	unsigned int	in;
> +	unsigned int	out;
> +	unsigned int	mask;
> +	unsigned int	esize;
> +	void		*data;
> +};
> +
> +#define __STRUCT_KFIFO_COMMON(datatype, recsize, ptrtype) \
> +	union { \
> +		struct __kfifo	kfifo; \
> +		datatype	*type; \
> +		char		(*rectype)[recsize]; \
> +		ptrtype		*ptr; \
> +		const ptrtype	*ptr_const; \
> +	}
> +
> +#define __STRUCT_KFIFO(type, size, recsize, ptrtype) \
> +{ \
> +	__STRUCT_KFIFO_COMMON(type, recsize, ptrtype); \
> +	type		buf[((size < 2) || (size & (size - 1))) ? -1 : size]; \
> +}
> +
> +#define STRUCT_KFIFO(type, size) \
> +	struct __STRUCT_KFIFO(type, size, 0, type)
> +
> +#define __STRUCT_KFIFO_PTR(type, recsize, ptrtype) \
> +{ \
> +	__STRUCT_KFIFO_COMMON(type, recsize, ptrtype); \
> +	type		buf[0]; \
> +}
> +
> +#define STRUCT_KFIFO_PTR(type) \
> +	struct __STRUCT_KFIFO_PTR(type, 0, type)
> +
> +/*
> + * define compatibility "struct kfifo" for dynamic allocated fifos
> + */
> +struct kfifo __STRUCT_KFIFO_PTR(unsigned char, 0, void);
> +
> +#define STRUCT_KFIFO_REC_1(size) \
> +	struct __STRUCT_KFIFO(unsigned char, size, 1, void)
> +
> +#define STRUCT_KFIFO_REC_2(size) \
> +	struct __STRUCT_KFIFO(unsigned char, size, 2, void)
> +
> +/*
> + * define kfifo_rec types
> + */
> +struct kfifo_rec_ptr_1 __STRUCT_KFIFO_PTR(unsigned char, 1, void);
> +struct kfifo_rec_ptr_2 __STRUCT_KFIFO_PTR(unsigned char, 2, void);
> +
> +/*
> + * helper macro to distinguish between real in place fifo where the fifo
> + * array is a part of the structure and the fifo type where the array is
> + * outside of the fifo structure.
> + */
> +#define	__is_kfifo_ptr(fifo)	(sizeof(*fifo) == sizeof(struct __kfifo))
> +
> +/**
> + * DECLARE_KFIFO_PTR - macro to declare a fifo pointer object
> + * @fifo: name of the declared fifo
> + * @type: type of the fifo elements
> + */
> +#define DECLARE_KFIFO_PTR(fifo, type)	STRUCT_KFIFO_PTR(type) fifo
> +
> +/**
> + * DECLARE_KFIFO - macro to declare a fifo object
> + * @fifo: name of the declared fifo
> + * @type: type of the fifo elements
> + * @size: the number of elements in the fifo, this must be a power of 2
> + */
> +#define DECLARE_KFIFO(fifo, type, size)	STRUCT_KFIFO(type, size) fifo
> +
> +/**
> + * INIT_KFIFO - Initialize a fifo declared by DECLARE_KFIFO
> + * @fifo: name of the declared fifo datatype
> + */
> +#define INIT_KFIFO(fifo) \
> +(void)({ \
> +	typeof(&(fifo)) __tmp = &(fifo); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	__kfifo->in = 0; \
> +	__kfifo->out = 0; \
> +	__kfifo->mask = __is_kfifo_ptr(__tmp) ? 0 : ARRAY_SIZE(__tmp->buf) - 1;\
> +	__kfifo->esize = sizeof(*__tmp->buf); \
> +	__kfifo->data = __is_kfifo_ptr(__tmp) ?  NULL : __tmp->buf; \
> +})
> +
> +/**
> + * DEFINE_KFIFO - macro to define and initialize a fifo
> + * @fifo: name of the declared fifo datatype
> + * @type: type of the fifo elements
> + * @size: the number of elements in the fifo, this must be a power of 2
> + *
> + * Note: the macro can be used for global and local fifo data type variables.
> + */
> +#define DEFINE_KFIFO(fifo, type, size) \
> +	DECLARE_KFIFO(fifo, type, size) = \
> +	(typeof(fifo)) { \
> +		{ \
> +			{ \
> +			.in	= 0, \
> +			.out	= 0, \
> +			.mask	= __is_kfifo_ptr(&(fifo)) ? \
> +				  0 : \
> +				  ARRAY_SIZE((fifo).buf) - 1, \
> +			.esize	= sizeof(*(fifo).buf), \
> +			.data	= __is_kfifo_ptr(&(fifo)) ? \
> +				NULL : \
> +				(fifo).buf, \
> +			} \
> +		} \
> +	}
> +
> +
> +static inline unsigned int __must_check
> +__kfifo_must_check_helper(unsigned int val)
> +{
> +	return val;
> +}
> +
> +/**
> + * kfifo_initialized - Check if the fifo is initialized
> + * @fifo: address of the fifo to check
> + *
> + * Return %true if fifo is initialized, otherwise %false.
> + * Assumes the fifo was 0 before.
> + */
> +#define kfifo_initialized(fifo) ((fifo)->kfifo.mask)
> +
> +/**
> + * kfifo_esize - returns the size of the element managed by the fifo
> + * @fifo: address of the fifo to be used
> + */
> +#define kfifo_esize(fifo)	((fifo)->kfifo.esize)
> +
> +/**
> + * kfifo_recsize - returns the size of the record length field
> + * @fifo: address of the fifo to be used
> + */
> +#define kfifo_recsize(fifo)	(sizeof(*(fifo)->rectype))
> +
> +/**
> + * kfifo_size - returns the size of the fifo in elements
> + * @fifo: address of the fifo to be used
> + */
> +#define kfifo_size(fifo)	((fifo)->kfifo.mask + 1)
> +
> +/**
> + * kfifo_reset - removes the entire fifo content
> + * @fifo: address of the fifo to be used
> + *
> + * Note: usage of kfifo_reset() is dangerous. It should be only called when the
> + * fifo is exclusived locked or when it is secured that no other thread is
> + * accessing the fifo.
> + */
> +#define kfifo_reset(fifo) \
> +(void)({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	__tmp->kfifo.in = __tmp->kfifo.out = 0; \
> +})
> +
> +/**
> + * kfifo_reset_out - skip fifo content
> + * @fifo: address of the fifo to be used
> + *
> + * Note: The usage of kfifo_reset_out() is safe until it will be only called
> + * from the reader thread and there is only one concurrent reader. Otherwise
> + * it is dangerous and must be handled in the same way as kfifo_reset().
> + */
> +#define kfifo_reset_out(fifo)	\
> +(void)({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	__tmp->kfifo.out = __tmp->kfifo.in; \
> +})
> +
> +/**
> + * kfifo_len - returns the number of used elements in the fifo
> + * @fifo: address of the fifo to be used
> + */
> +#define kfifo_len(fifo) \
> +({ \
> +	typeof(fifo + 1) __tmpl = (fifo); \
> +	__tmpl->kfifo.in - __tmpl->kfifo.out; \
> +})
> +
> +/**
> + * kfifo_is_empty - returns true if the fifo is empty
> + * @fifo: address of the fifo to be used
> + */
> +#define	kfifo_is_empty(fifo) \
> +({ \
> +	typeof(fifo + 1) __tmpq = (fifo); \
> +	__tmpq->kfifo.in == __tmpq->kfifo.out; \
> +})
> +
> +/**
> + * kfifo_is_full - returns true if the fifo is full
> + * @fifo: address of the fifo to be used
> + */
> +#define	kfifo_is_full(fifo) \
> +({ \
> +	typeof(fifo + 1) __tmpq = (fifo); \
> +	kfifo_len(__tmpq) > __tmpq->kfifo.mask; \
> +})
> +
> +/**
> + * kfifo_avail - returns the number of unused elements in the fifo
> + * @fifo: address of the fifo to be used
> + */
> +#define	kfifo_avail(fifo) \
> +__kfifo_must_check_helper( \
> +({ \
> +	typeof(fifo + 1) __tmpq = (fifo); \
> +	const size_t __recsize = sizeof(*__tmpq->rectype); \
> +	unsigned int __avail = kfifo_size(__tmpq) - kfifo_len(__tmpq); \
> +	(__recsize) ? ((__avail <= __recsize) ? 0 : \
> +	__kfifo_max_r(__avail - __recsize, __recsize)) : \
> +	__avail; \
> +}) \
> +)
> +
> +/**
> + * kfifo_skip - skip output data
> + * @fifo: address of the fifo to be used
> + */
> +#define	kfifo_skip(fifo) \
> +(void)({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	if (__recsize) \
> +		__kfifo_skip_r(__kfifo, __recsize); \
> +	else \
> +		__kfifo->out++; \
> +})
> +
> +/**
> + * kfifo_peek_len - gets the size of the next fifo record
> + * @fifo: address of the fifo to be used
> + *
> + * This function returns the size of the next fifo record in number of bytes.
> + */
> +#define kfifo_peek_len(fifo) \
> +__kfifo_must_check_helper( \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	(!__recsize) ? kfifo_len(__tmp) * sizeof(*__tmp->type) : \
> +	__kfifo_len_r(__kfifo, __recsize); \
> +}) \
> +)
> +
> +/**
> + * kfifo_alloc - dynamically allocates a new fifo buffer
> + * @fifo: pointer to the fifo
> + * @size: the number of elements in the fifo, this must be a power of 2
> + * @gfp_mask: get_free_pages mask, passed to kmalloc()
> + *
> + * This macro dynamically allocates a new fifo buffer.
> + *
> + * The numer of elements will be rounded-up to a power of 2.
> + * The fifo will be release with kfifo_free().
> + * Return 0 if no error, otherwise an error code.
> + */
> +#define kfifo_alloc(fifo, size, gfp_mask) \
> +__kfifo_must_check_helper( \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	__is_kfifo_ptr(__tmp) ? \
> +	__kfifo_alloc(__kfifo, size, sizeof(*__tmp->type), gfp_mask) : \
> +	-EINVAL; \
> +}) \
> +)
> +
> +/**
> + * kfifo_free - frees the fifo
> + * @fifo: the fifo to be freed
> + */
> +#define kfifo_free(fifo) \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	if (__is_kfifo_ptr(__tmp)) \
> +		__kfifo_free(__kfifo); \
> +})
> +
> +/**
> + * kfifo_init - initialize a fifo using a preallocated buffer
> + * @fifo: the fifo to assign the buffer
> + * @buffer: the preallocated buffer to be used
> + * @size: the size of the internal buffer, this have to be a power of 2
> + *
> + * This macro initialize a fifo using a preallocated buffer.
> + *
> + * The numer of elements will be rounded-up to a power of 2.
> + * Return 0 if no error, otherwise an error code.
> + */
> +#define kfifo_init(fifo, buffer, size) \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	__is_kfifo_ptr(__tmp) ? \
> +	__kfifo_init(__kfifo, buffer, size, sizeof(*__tmp->type)) : \
> +	-EINVAL; \
> +})
> +
> +/**
> + * kfifo_put - put data into the fifo
> + * @fifo: address of the fifo to be used
> + * @val: the data to be added
> + *
> + * This macro copies the given value into the fifo.
> + * It returns 0 if the fifo was full. Otherwise it returns the number
> + * processed elements.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macro.
> + */
> +#define	kfifo_put(fifo, val) \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	typeof(val + 1) __val = (val); \
> +	unsigned int __ret; \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	if (0) { \
> +		typeof(__tmp->ptr_const) __dummy __attribute__ ((unused)); \
> +		__dummy = (typeof(__val))NULL; \
> +	} \
> +	if (__recsize) \
> +		__ret = __kfifo_in_r(__kfifo, __val, sizeof(*__val), \
> +			__recsize); \
> +	else { \
> +		__ret = !kfifo_is_full(__tmp); \
> +		if (__ret) { \
> +			(__is_kfifo_ptr(__tmp) ? \
> +			((typeof(__tmp->type))__kfifo->data) : \
> +			(__tmp->buf) \
> +			)[__kfifo->in & __tmp->kfifo.mask] = \
> +				*(typeof(__tmp->type))__val; \
> +			smp_wmb(); \
> +			__kfifo->in++; \
> +		} \
> +	} \
> +	__ret; \
> +})
> +
> +/**
> + * kfifo_get - get data from the fifo
> + * @fifo: address of the fifo to be used
> + * @val: the var where to store the data to be added
> + *
> + * This macro reads the data from the fifo.
> + * It returns 0 if the fifo was empty. Otherwise it returns the number
> + * processed elements.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macro.
> + */
> +#define	kfifo_get(fifo, val) \
> +__kfifo_must_check_helper( \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	typeof(val + 1) __val = (val); \
> +	unsigned int __ret; \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	if (0) \
> +		__val = (typeof(__tmp->ptr))0; \
> +	if (__recsize) \
> +		__ret = __kfifo_out_r(__kfifo, __val, sizeof(*__val), \
> +			__recsize); \
> +	else { \
> +		__ret = !kfifo_is_empty(__tmp); \
> +		if (__ret) { \
> +			*(typeof(__tmp->type))__val = \
> +				(__is_kfifo_ptr(__tmp) ? \
> +				((typeof(__tmp->type))__kfifo->data) : \
> +				(__tmp->buf) \
> +				)[__kfifo->out & __tmp->kfifo.mask]; \
> +			smp_wmb(); \
> +			__kfifo->out++; \
> +		} \
> +	} \
> +	__ret; \
> +}) \
> +)
> +
> +/**
> + * kfifo_peek - get data from the fifo without removing
> + * @fifo: address of the fifo to be used
> + * @val: the var where to store the data to be added
> + *
> + * This reads the data from the fifo without removing it from the fifo.
> + * It returns 0 if the fifo was empty. Otherwise it returns the number
> + * processed elements.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macro.
> + */
> +#define	kfifo_peek(fifo, val) \
> +__kfifo_must_check_helper( \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	typeof(val + 1) __val = (val); \
> +	unsigned int __ret; \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	if (0) \
> +		__val = (typeof(__tmp->ptr))NULL; \
> +	if (__recsize) \
> +		__ret = __kfifo_out_peek_r(__kfifo, __val, sizeof(*__val), \
> +			__recsize); \
> +	else { \
> +		__ret = !kfifo_is_empty(__tmp); \
> +		if (__ret) { \
> +			*(typeof(__tmp->type))__val = \
> +				(__is_kfifo_ptr(__tmp) ? \
> +				((typeof(__tmp->type))__kfifo->data) : \
> +				(__tmp->buf) \
> +				)[__kfifo->out & __tmp->kfifo.mask]; \
> +			smp_wmb(); \
> +		} \
> +	} \
> +	__ret; \
> +}) \
> +)
> +
> +/**
> + * kfifo_in - put data into the fifo
> + * @fifo: address of the fifo to be used
> + * @buf: the data to be added
> + * @n: number of elements to be added
> + *
> + * This macro copies the given buffer into the fifo and returns the
> + * number of copied elements.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macro.
> + */
> +#define	kfifo_in(fifo, buf, n) \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	typeof(buf + 1) __buf = (buf); \
> +	unsigned long __n = (n); \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	if (0) { \
> +		typeof(__tmp->ptr_const) __dummy __attribute__ ((unused)); \
> +		__dummy = (typeof(__buf))NULL; \
> +	} \
> +	(__recsize) ?\
> +	__kfifo_in_r(__kfifo, __buf, __n, __recsize) : \
> +	__kfifo_in(__kfifo, __buf, __n); \
> +})
> +
> +/**
> + * kfifo_in_spinlocked - put data into the fifo using a spinlock for locking
> + * @fifo: address of the fifo to be used
> + * @buf: the data to be added
> + * @n: number of elements to be added
> + * @lock: pointer to the spinlock to use for locking
> + *
> + * This macro copies the given values buffer into the fifo and returns the
> + * number of copied elements.
> + */
> +#define	kfifo_in_spinlocked(fifo, buf, n, lock) \
> +({ \
> +	unsigned long __flags; \
> +	unsigned int __ret; \
> +	spin_lock_irqsave(lock, __flags); \
> +	__ret = kfifo_in(fifo, buf, n); \
> +	spin_unlock_irqrestore(lock, __flags); \
> +	__ret; \
> +})
> +
> +/* alias for kfifo_in_spinlocked, will be removed in a future release */
> +#define kfifo_in_locked(fifo, buf, n, lock) \
> +		kfifo_in_spinlocked(fifo, buf, n, lock)
> +
> +/**
> + * kfifo_out - get data from the fifo
> + * @fifo: address of the fifo to be used
> + * @buf: pointer to the storage buffer
> + * @n: max. number of elements to get
> + *
> + * This macro get some data from the fifo and return the numbers of elements
> + * copied.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macro.
> + */
> +#define	kfifo_out(fifo, buf, n) \
> +__kfifo_must_check_helper( \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	typeof(buf + 1) __buf = (buf); \
> +	unsigned long __n = (n); \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	if (0) { \
> +		typeof(__tmp->ptr) __dummy = NULL; \
> +		__buf = __dummy; \
> +	} \
> +	(__recsize) ?\
> +	__kfifo_out_r(__kfifo, __buf, __n, __recsize) : \
> +	__kfifo_out(__kfifo, __buf, __n); \
> +}) \
> +)
> +
> +/**
> + * kfifo_out_spinlocked - get data from the fifo using a spinlock for locking
> + * @fifo: address of the fifo to be used
> + * @buf: pointer to the storage buffer
> + * @n: max. number of elements to get
> + * @lock: pointer to the spinlock to use for locking
> + *
> + * This macro get the data from the fifo and return the numbers of elements
> + * copied.
> + */
> +#define	kfifo_out_spinlocked(fifo, buf, n, lock) \
> +__kfifo_must_check_helper( \
> +({ \
> +	unsigned long __flags; \
> +	unsigned int __ret; \
> +	spin_lock_irqsave(lock, __flags); \
> +	__ret = kfifo_out(fifo, buf, n); \
> +	spin_unlock_irqrestore(lock, __flags); \
> +	__ret; \
> +}) \
> +)
> +
> +/* alias for kfifo_out_spinlocked, will be removed in a future release */
> +#define kfifo_out_locked(fifo, buf, n, lock) \
> +		kfifo_out_spinlocked(fifo, buf, n, lock)
> +
> +/**
> + * kfifo_from_user - puts some data from user space into the fifo
> + * @fifo: address of the fifo to be used
> + * @from: pointer to the data to be added
> + * @len: the length of the data to be added
> + * @copied: pointer to output variable to store the number of copied bytes
> + *
> + * This macro copies at most @len bytes from the @from into the
> + * fifo, depending of the available space and returns -EFAULT/0.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macro.
> + */
> +#define	kfifo_from_user(fifo, from, len, copied) \
> +__kfifo_must_check_helper( \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	const void __user *__from = (from); \
> +	unsigned int __len = (len); \
> +	unsigned int *__copied = (copied); \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	(__recsize) ? \
> +	__kfifo_from_user_r(__kfifo, __from, __len,  __copied, __recsize) : \
> +	__kfifo_from_user(__kfifo, __from, __len, __copied); \
> +}) \
> +)
> +
> +/**
> + * kfifo_to_user - copies data from the fifo into user space
> + * @fifo: address of the fifo to be used
> + * @to: where the data must be copied
> + * @len: the size of the destination buffer
> + * @copied: pointer to output variable to store the number of copied bytes
> + *
> + * This macro copies at most @len bytes from the fifo into the
> + * @to buffer and returns -EFAULT/0.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macro.
> + */
> +#define	kfifo_to_user(fifo, to, len, copied) \
> +__kfifo_must_check_helper( \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	void __user *__to = (to); \
> +	unsigned int __len = (len); \
> +	unsigned int *__copied = (copied); \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	(__recsize) ? \
> +	__kfifo_to_user_r(__kfifo, __to, __len, __copied, __recsize) : \
> +	__kfifo_to_user(__kfifo, __to, __len, __copied); \
> +}) \
> +)
> +
> +/**
> + * kfifo_dma_in_prepare - setup a scatterlist for DMA input
> + * @fifo: address of the fifo to be used
> + * @sgl: pointer to the scatterlist array
> + * @nents: number of entries in the scatterlist array
> + * @len: number of elements to transfer
> + *
> + * This macro fills a scatterlist for DMA input.
> + * It returns the number entries in the scatterlist array.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macros.
> + */
> +#define	kfifo_dma_in_prepare(fifo, sgl, nents, len) \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	struct scatterlist *__sgl = (sgl); \
> +	int __nents = (nents); \
> +	unsigned int __len = (len); \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	(__recsize) ? \
> +	__kfifo_dma_in_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) : \
> +	__kfifo_dma_in_prepare(__kfifo, __sgl, __nents, __len); \
> +})
> +
> +/**
> + * kfifo_dma_in_finish - finish a DMA IN operation
> + * @fifo: address of the fifo to be used
> + * @len: number of bytes to received
> + *
> + * This macro finish a DMA IN operation. The in counter will be updated by
> + * the len parameter. No error checking will be done.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macros.
> + */
> +#define kfifo_dma_in_finish(fifo, len) \
> +(void)({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	unsigned int __len = (len); \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	if (__recsize) \
> +		__kfifo_dma_in_finish_r(__kfifo, __len, __recsize); \
> +	else \
> +		__kfifo->in += __len / sizeof(*__tmp->type); \
> +})
> +
> +/**
> + * kfifo_dma_out_prepare - setup a scatterlist for DMA output
> + * @fifo: address of the fifo to be used
> + * @sgl: pointer to the scatterlist array
> + * @nents: number of entries in the scatterlist array
> + * @len: number of elements to transfer
> + *
> + * This macro fills a scatterlist for DMA output which at most @len bytes
> + * to transfer.
> + * It returns the number entries in the scatterlist array.
> + * A zero means there is no space available and the scatterlist is not filled.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macros.
> + */
> +#define	kfifo_dma_out_prepare(fifo, sgl, nents, len) \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	struct scatterlist *__sgl = (sgl); \
> +	int __nents = (nents); \
> +	unsigned int __len = (len); \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	(__recsize) ? \
> +	__kfifo_dma_out_prepare_r(__kfifo, __sgl, __nents, __len, __recsize) : \
> +	__kfifo_dma_out_prepare(__kfifo, __sgl, __nents, __len); \
> +})
> +
> +/**
> + * kfifo_dma_out_finish - finish a DMA OUT operation
> + * @fifo: address of the fifo to be used
> + * @len: number of bytes transferd
> + *
> + * This macro finish a DMA OUT operation. The out counter will be updated by
> + * the len parameter. No error checking will be done.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macros.
> + */
> +#define kfifo_dma_out_finish(fifo, len) \
> +(void)({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	unsigned int __len = (len); \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	if (__recsize) \
> +		__kfifo_dma_out_finish_r(__kfifo, __recsize); \
> +	else \
> +		__kfifo->out += __len / sizeof(*__tmp->type); \
> +})
> +
> +/**
> + * kfifo_out_peek - gets some data from the fifo
> + * @fifo: address of the fifo to be used
> + * @buf: pointer to the storage buffer
> + * @n: max. number of elements to get
> + *
> + * This macro get the data from the fifo and return the numbers of elements
> + * copied. The data is not removed from the fifo.
> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these macro.
> + */
> +#define	kfifo_out_peek(fifo, buf, n) \
> +__kfifo_must_check_helper( \
> +({ \
> +	typeof(fifo + 1) __tmp = (fifo); \
> +	typeof(buf + 1) __buf = (buf); \
> +	unsigned long __n = (n); \
> +	const size_t __recsize = sizeof(*__tmp->rectype); \
> +	struct __kfifo *__kfifo = &__tmp->kfifo; \
> +	if (0) { \
> +		typeof(__tmp->ptr) __dummy __attribute__ ((unused)) = NULL; \
> +		__buf = __dummy; \
> +	} \
> +	(__recsize) ? \
> +	__kfifo_out_peek_r(__kfifo, __buf, __n, __recsize) : \
> +	__kfifo_out_peek(__kfifo, __buf, __n); \
> +}) \
> +)
> +
> +extern int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
> +	size_t esize, gfp_t gfp_mask);
> +
> +extern void __kfifo_free(struct __kfifo *fifo);
> +
> +extern int __kfifo_init(struct __kfifo *fifo, void *buffer,
> +	unsigned int size, size_t esize);
> +
> +extern unsigned int __kfifo_in(struct __kfifo *fifo,
> +	const void *buf, unsigned int len);
> +
> +extern unsigned int __kfifo_out(struct __kfifo *fifo,
> +	void *buf, unsigned int len);
> +
> +extern int __kfifo_from_user(struct __kfifo *fifo,
> +	const void __user *from, unsigned long len, unsigned int *copied);
> +
> +extern int __kfifo_to_user(struct __kfifo *fifo,
> +	void __user *to, unsigned long len, unsigned int *copied);
> +
> +extern unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
> +	struct scatterlist *sgl, int nents, unsigned int len);
> +
> +extern unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
> +	struct scatterlist *sgl, int nents, unsigned int len);
> +
> +extern unsigned int __kfifo_out_peek(struct __kfifo *fifo,
> +	void *buf, unsigned int len);
> +
> +extern unsigned int __kfifo_in_r(struct __kfifo *fifo,
> +	const void *buf, unsigned int len, size_t recsize);
> +
> +extern unsigned int __kfifo_out_r(struct __kfifo *fifo,
> +	void *buf, unsigned int len, size_t recsize);
> +
> +extern int __kfifo_from_user_r(struct __kfifo *fifo,
> +	const void __user *from, unsigned long len, unsigned int *copied,
> +	size_t recsize);
> +
> +extern int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
> +	unsigned long len, unsigned int *copied, size_t recsize);
> +
> +extern unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
> +	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize);
> +
> +extern void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
> +	unsigned int len, size_t recsize);
> +
> +extern unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
> +	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize);
> +
> +extern void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize);
> +
> +extern unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize);
> +
> +extern unsigned int __kfifo_out_peek_r(struct __kfifo *fifo,
> +	void *buf, unsigned int len, size_t recsize);
> +
> +extern unsigned int __kfifo_max_r(unsigned int len, size_t recsize);
> +
> +#endif
> diff --git a/kernel/kfifo-new.c b/kernel/kfifo-new.c
> new file mode 100644
> index 0000000..02192dd
> --- /dev/null
> +++ b/kernel/kfifo-new.c
> @@ -0,0 +1,602 @@
> +/*
> + * A generic kernel FIFO implementation
> + *
> + * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/err.h>
> +#include <linux/log2.h>
> +#include <linux/uaccess.h>
> +#include <linux/kfifo.h>
> +
> +/*
> + * internal helper to calculate the unused elements in a fifo
> + */
> +static inline unsigned int kfifo_unused(struct __kfifo *fifo)
> +{
> +	return (fifo->mask + 1) - (fifo->in - fifo->out);
> +}
> +
> +int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
> +		size_t esize, gfp_t gfp_mask)
> +{
> +	/*
> +	 * round down to the next power of 2, since our 'let the indices
> +	 * wrap' technique works only in this case.
> +	 */
> +	if (!is_power_of_2(size))
> +		size = rounddown_pow_of_two(size);
> +
> +	fifo->in = 0;
> +	fifo->out = 0;
> +	fifo->esize = esize;
> +
> +	if (size < 2) {
> +		fifo->data = NULL;
> +		fifo->mask = 0;
> +		return -EINVAL;
> +	}
> +
> +	fifo->data = kmalloc(size * esize, gfp_mask);
> +
> +	if (!fifo->data) {
> +		fifo->mask = 0;
> +		return -ENOMEM;
> +	}
> +	fifo->mask = size - 1;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(__kfifo_alloc);
> +
> +void __kfifo_free(struct __kfifo *fifo)
> +{
> +	kfree(fifo->data);
> +	fifo->in = 0;
> +	fifo->out = 0;
> +	fifo->esize = 0;
> +	fifo->data = NULL;
> +	fifo->mask = 0;
> +}
> +EXPORT_SYMBOL(__kfifo_free);
> +
> +int __kfifo_init(struct __kfifo *fifo, void *buffer,
> +		unsigned int size, size_t esize)
> +{
> +	size /= esize;
> +
> +	if (!is_power_of_2(size))
> +		size = rounddown_pow_of_two(size);
> +
> +	fifo->in = 0;
> +	fifo->out = 0;
> +	fifo->esize = esize;
> +	fifo->data = buffer;
> +
> +	if (size < 2) {
> +		fifo->mask = 0;
> +		return -EINVAL;
> +	}
> +	fifo->mask = size - 1;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(__kfifo_init);
> +
> +static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
> +		unsigned int len, unsigned int off)
> +{
> +	unsigned int size = fifo->mask + 1;
> +	unsigned int esize = fifo->esize;
> +	unsigned int l;
> +
> +	off &= fifo->mask;
> +	if (esize != 1) {
> +		off *= esize;
> +		size *= esize;
> +		len *= esize;
> +	}
> +	l = min(len, size - off);
> +
> +	memcpy(fifo->data + off, src, l);
> +	memcpy(fifo->data, src + l, len - l);
> +	/*
> +	 * make sure that the data in the fifo is up to date before
> +	 * incrementing the fifo->in index counter
> +	 */
> +	smp_wmb();
> +}
> +
> +unsigned int __kfifo_in(struct __kfifo *fifo,
> +		const void *buf, unsigned int len)
> +{
> +	unsigned int l;
> +
> +	l = kfifo_unused(fifo);
> +	if (len > l)
> +		len = l;
> +
> +	kfifo_copy_in(fifo, buf, len, fifo->in);
> +	fifo->in += len;
> +	return len;
> +}
> +EXPORT_SYMBOL(__kfifo_in);
> +
> +static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
> +		unsigned int len, unsigned int off)
> +{
> +	unsigned int size = fifo->mask + 1;
> +	unsigned int esize = fifo->esize;
> +	unsigned int l;
> +
> +	off &= fifo->mask;
> +	if (esize != 1) {
> +		off *= esize;
> +		size *= esize;
> +		len *= esize;
> +	}
> +	l = min(len, size - off);
> +
> +	memcpy(dst, fifo->data + off, l);
> +	memcpy(dst + l, fifo->data, len - l);
> +	/*
> +	 * make sure that the data is copied before
> +	 * incrementing the fifo->out index counter
> +	 */
> +	smp_wmb();
> +}
> +
> +unsigned int __kfifo_out_peek(struct __kfifo *fifo,
> +		void *buf, unsigned int len)
> +{
> +	unsigned int l;
> +
> +	l = fifo->in - fifo->out;
> +	if (len > l)
> +		len = l;
> +
> +	kfifo_copy_out(fifo, buf, len, fifo->out);
> +	return len;
> +}
> +EXPORT_SYMBOL(__kfifo_out_peek);
> +
> +unsigned int __kfifo_out(struct __kfifo *fifo,
> +		void *buf, unsigned int len)
> +{
> +	len = __kfifo_out_peek(fifo, buf, len);
> +	fifo->out += len;
> +	return len;
> +}
> +EXPORT_SYMBOL(__kfifo_out);
> +
> +static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
> +	const void __user *from, unsigned int len, unsigned int off,
> +	unsigned int *copied)
> +{
> +	unsigned int size = fifo->mask + 1;
> +	unsigned int esize = fifo->esize;
> +	unsigned int l;
> +	unsigned long ret;
> +
> +	off &= fifo->mask;
> +	if (esize != 1) {
> +		off *= esize;
> +		size *= esize;
> +		len *= esize;
> +	}
> +	l = min(len, size - off);
> +
> +	ret = copy_from_user(fifo->data + off, from, l);
> +	if (unlikely(ret))
> +		ret = DIV_ROUND_UP(ret + len - l, esize);
> +	else {
> +		ret = copy_from_user(fifo->data, from + l, len - l);
> +		if (unlikely(ret))
> +			ret = DIV_ROUND_UP(ret, esize);
> +	}
> +	/*
> +	 * make sure that the data in the fifo is up to date before
> +	 * incrementing the fifo->in index counter
> +	 */
> +	smp_wmb();
> +	*copied = len - ret;
> +	/* return the number of elements which are not copied */
> +	return ret;
> +}
> +
> +int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
> +		unsigned long len, unsigned int *copied)
> +{
> +	unsigned int l;
> +	unsigned long ret;
> +	unsigned int esize = fifo->esize;
> +	int err;
> +
> +	if (esize != 1)
> +		len /= esize;
> +
> +	l = kfifo_unused(fifo);
> +	if (len > l)
> +		len = l;
> +
> +	ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
> +	if (unlikely(ret)) {
> +		len -= ret;
> +		err = -EFAULT;
> +	} else
> +		err = 0;
> +	fifo->in += len;
> +	return err;
> +}
> +EXPORT_SYMBOL(__kfifo_from_user);
> +
> +static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
> +		unsigned int len, unsigned int off, unsigned int *copied)
> +{
> +	unsigned int l;
> +	unsigned long ret;
> +	unsigned int size = fifo->mask + 1;
> +	unsigned int esize = fifo->esize;
> +
> +	off &= fifo->mask;
> +	if (esize != 1) {
> +		off *= esize;
> +		size *= esize;
> +		len *= esize;
> +	}
> +	l = min(len, size - off);
> +
> +	ret = copy_to_user(to, fifo->data + off, l);
> +	if (unlikely(ret))
> +		ret = DIV_ROUND_UP(ret + len - l, esize);
> +	else {
> +		ret = copy_to_user(to + l, fifo->data, len - l);
> +		if (unlikely(ret))
> +			ret = DIV_ROUND_UP(ret, esize);
> +	}
> +	/*
> +	 * make sure that the data is copied before
> +	 * incrementing the fifo->out index counter
> +	 */
> +	smp_wmb();
> +	*copied = len - ret;
> +	/* return the number of elements which are not copied */
> +	return ret;
> +}
> +
> +int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
> +		unsigned long len, unsigned int *copied)
> +{
> +	unsigned int l;
> +	unsigned long ret;
> +	unsigned int esize = fifo->esize;
> +	int err;
> +
> +	if (esize != 1)
> +		len /= esize;
> +
> +	l = fifo->in - fifo->out;
> +	if (len > l)
> +		len = l;
> +	ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
> +	if (unlikely(ret)) {
> +		len -= ret;
> +		err = -EFAULT;
> +	} else
> +		err = 0;
> +	fifo->out += len;
> +	return err;
> +}
> +EXPORT_SYMBOL(__kfifo_to_user);
> +
> +static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
> +		int nents, unsigned int len)
> +{
> +	int n;
> +	unsigned int l;
> +	unsigned int off;
> +	struct page *page;
> +
> +	if (!nents)
> +		return 0;
> +
> +	if (!len)
> +		return 0;
> +
> +	n = 0;
> +	page = virt_to_page(buf);
> +	off = offset_in_page(buf);
> +	l = 0;
> +
> +	while (len >= l + PAGE_SIZE - off) {
> +		struct page *npage;
> +
> +		l += PAGE_SIZE;
> +		buf += PAGE_SIZE;
> +		npage = virt_to_page(buf);
> +		if (page_to_phys(page) != page_to_phys(npage) - l) {
> +			sgl->page_link = 0;
> +			sg_set_page(sgl++, page, l - off, off);
> +			if (++n == nents)
> +				return n;
> +			page = npage;
> +			len -= l - off;
> +			l = off = 0;
> +		}
> +	}
> +	sgl->page_link = 0;
> +	sg_set_page(sgl++, page, len, off);
> +	return n + 1;
> +}

Hello Stefani,

I'm a bit concerned about the use of scatterlists here. I think that you
should be using sg_next(sgl) to get the next scatterlist entry. Just
incrementing the pointer will not work with chained scatterlists. See
struct sg_table in include/linux/scatterlist.h.

After you make this change, I don't think you'll need to explicity set
the sgl->page_link member anymore.

Jens, can you comment on the use of scatterlists here?

I hope this patch finally makes it in during this merge window. I'm
ready to start porting one of my drivers to use the DMA features. As
GregKH suggested, I'll submit them for mainline after I port to this
API.

Ira

> +
> +static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
> +		int nents, unsigned int len, unsigned int off)
> +{
> +	unsigned int size = fifo->mask + 1;
> +	unsigned int esize = fifo->esize;
> +	unsigned int l;
> +	unsigned int n;
> +
> +	off &= fifo->mask;
> +	if (esize != 1) {
> +		off *= esize;
> +		size *= esize;
> +		len *= esize;
> +	}
> +	l = min(len, size - off);
> +
> +	n  = setup_sgl_buf(sgl, fifo->data + off, nents, l);
> +	n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
> +
> +	if (n)
> +		sg_mark_end(sgl + n - 1);
> +	return n;
> +}
> +
> +unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
> +		struct scatterlist *sgl, int nents, unsigned int len)
> +{
> +	unsigned int l;
> +
> +	l = kfifo_unused(fifo);
> +	if (len > l)
> +		len = l;
> +
> +	return setup_sgl(fifo, sgl, nents, len, fifo->in);
> +}
> +EXPORT_SYMBOL(__kfifo_dma_in_prepare);
> +
> +unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
> +		struct scatterlist *sgl, int nents, unsigned int len)
> +{
> +	unsigned int l;
> +
> +	l = fifo->in - fifo->out;
> +	if (len > l)
> +		len = l;
> +
> +	return setup_sgl(fifo, sgl, nents, len, fifo->out);
> +}
> +EXPORT_SYMBOL(__kfifo_dma_out_prepare);
> +
> +unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
> +{
> +	unsigned int max = (1 << (recsize << 3)) - 1;
> +
> +	if (len > max)
> +		return max;
> +	return len;
> +}
> +
> +#define	__KFIFO_PEEK(data, out, mask) \
> +	((data)[(out) & (mask)])
> +/*
> + * __kfifo_peek_n internal helper function for determinate the length of
> + * the next record in the fifo
> + */
> +static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
> +{
> +	unsigned int l;
> +	unsigned int mask = fifo->mask;
> +	unsigned char *data = fifo->data;
> +
> +	l = __KFIFO_PEEK(data, fifo->out, mask);
> +
> +	if (--recsize)
> +		l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
> +
> +	return l;
> +}
> +
> +#define	__KFIFO_POKE(data, in, mask, val) \
> +	( \
> +	(data)[(in) & (mask)] = (unsigned char)(val) \
> +	)
> +
> +/*
> + * __kfifo_poke_n internal helper function for storeing the length of
> + * the record into the fifo
> + */
> +static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
> +{
> +	unsigned int mask = fifo->mask;
> +	unsigned char *data = fifo->data;
> +
> +	__KFIFO_POKE(data, fifo->in, mask, n);
> +
> +	if (recsize > 1)
> +		__KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
> +}
> +
> +unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
> +{
> +	return __kfifo_peek_n(fifo, recsize);
> +}
> +EXPORT_SYMBOL(__kfifo_len_r);
> +
> +unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
> +		unsigned int len, size_t recsize)
> +{
> +	if (len + recsize > kfifo_unused(fifo))
> +		return 0;
> +
> +	__kfifo_poke_n(fifo, len, recsize);
> +
> +	kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
> +	fifo->in += len + recsize;
> +	return len;
> +}
> +EXPORT_SYMBOL(__kfifo_in_r);
> +
> +static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
> +	void *buf, unsigned int len, size_t recsize, unsigned int *n)
> +{
> +	*n = __kfifo_peek_n(fifo, recsize);
> +
> +	if (len > *n)
> +		len = *n;
> +
> +	kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
> +	return len;
> +}
> +
> +unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
> +		unsigned int len, size_t recsize)
> +{
> +	unsigned int n;
> +
> +	if (fifo->in == fifo->out)
> +		return 0;
> +
> +	return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
> +}
> +EXPORT_SYMBOL(__kfifo_out_peek_r);
> +
> +unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
> +		unsigned int len, size_t recsize)
> +{
> +	unsigned int n;
> +
> +	if (fifo->in == fifo->out)
> +		return 0;
> +
> +	len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
> +	fifo->out += n + recsize;
> +	return len;
> +}
> +EXPORT_SYMBOL(__kfifo_out_r);
> +
> +int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
> +	unsigned long len, unsigned int *copied, size_t recsize)
> +{
> +	unsigned long ret;
> +
> +	len = __kfifo_max_r(len, recsize);
> +
> +	if (len + recsize > kfifo_unused(fifo)) {
> +		*copied = 0;
> +		return 0;
> +	}
> +
> +	__kfifo_poke_n(fifo, len, recsize);
> +
> +	ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
> +	if (unlikely(ret)) {
> +		*copied = 0;
> +		return -EFAULT;
> +	}
> +	fifo->in += len + recsize;
> +	return 0;
> +}
> +EXPORT_SYMBOL(__kfifo_from_user_r);
> +
> +int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
> +	unsigned long len, unsigned int *copied, size_t recsize)
> +{
> +	unsigned long ret;
> +	unsigned int n;
> +
> +	if (fifo->in == fifo->out) {
> +		*copied = 0;
> +		return 0;
> +	}
> +
> +	n = __kfifo_peek_n(fifo, recsize);
> +	if (len > n)
> +		len = n;
> +
> +	ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
> +	if (unlikely(ret)) {
> +		*copied = 0;
> +		return -EFAULT;
> +	}
> +	fifo->out += n + recsize;
> +	return 0;
> +}
> +EXPORT_SYMBOL(__kfifo_to_user_r);
> +
> +unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
> +	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
> +{
> +	if (!nents)
> +		BUG();
> +
> +	len = __kfifo_max_r(len, recsize);
> +
> +	if (len + recsize > kfifo_unused(fifo))
> +		return 0;
> +
> +	return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
> +}
> +EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
> +
> +void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
> +	unsigned int len, size_t recsize)
> +{
> +	len = __kfifo_max_r(len, recsize);
> +	__kfifo_poke_n(fifo, len, recsize);
> +	fifo->in += len + recsize;
> +}
> +EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
> +
> +unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
> +	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
> +{
> +	if (!nents)
> +		BUG();
> +
> +	len = __kfifo_max_r(len, recsize);
> +
> +	if (len + recsize > fifo->in - fifo->out)
> +		return 0;
> +
> +	return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
> +}
> +EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
> +
> +void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
> +{
> +	unsigned int len;
> +
> +	len = __kfifo_peek_n(fifo, recsize);
> +	fifo->out += len + recsize;
> +}
> +EXPORT_SYMBOL(__kfifo_dma_out_finish_r);
> -- 
> 1.7.0.4
> 

Re: [PATCH 2/4] add the new generic kfifo API

[Stefani Seibold]

Hi Ira,

please don't send me back the hole patch. If you want enhance something,
please write a clean patch which can i apply against the generic API
patch.

Stefani

Re: [PATCH 2/4] add the new generic kfifo API

[Ira W. Snyder]

On Sat, May 29, 2010 at 08:48:14PM +0200, Stefani Seibold wrote:
> Hi Ira,
> 
> please don't send me back the hole patch. If you want enhance something,
> please write a clean patch which can i apply against the generic API
> patch.
> 

If you looked down far enough, I put my comments inline. I should have
snipped out the extra noise, sorry.

Here is a completely untested patch that should fix kfifo when used with
chained scatterlists (AKA struct sg_table). Feel free to roll it into
the main patch.

Ira

>From 01d90fc6fb35e16b034f0893cd717af51c690cc7 Mon Sep 17 00:00:00 2001
From: Ira W. Snyder <kernel@irasnyder.com>
Date: Sat, 29 May 2010 12:02:47 -0700
Subject: [PATCH] kfifo: fix scatterlist usage

The current kfifo scatterlist implementation will not work with chained
scatterlists. It assumes that struct scatterlist arrays are allocated
contiguously, which is not the case when chained scatterlists (struct
sg_table) are in use.

Signed-off-by: Ira W. Snyder <kernel@irasnyder.com>
---
 kernel/kfifo.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/kernel/kfifo.c b/kernel/kfifo.c
index 02192dd..bd4e083 100644
--- a/kernel/kfifo.c
+++ b/kernel/kfifo.c
@@ -333,17 +333,16 @@ static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
 		buf += PAGE_SIZE;
 		npage = virt_to_page(buf);
 		if (page_to_phys(page) != page_to_phys(npage) - l) {
-			sgl->page_link = 0;
-			sg_set_page(sgl++, page, l - off, off);
-			if (++n == nents)
+			sg_set_page(sgl, page, l - off, off);
+			sgl = sg_next(sgl);
+			if (++n == nents || sgl == NULL)
 				return n;
 			page = npage;
 			len -= l - off;
 			l = off = 0;
 		}
 	}
-	sgl->page_link = 0;
-	sg_set_page(sgl++, page, len, off);
+	sg_set_page(sgl, page, len, off);
 	return n + 1;
 }
 
-- 
1.7.1

[PATCH 4/4] add example files to the kernel sample directory

[stefani]

From: Stefani Seibold <stefani@seibold.net>

This patch add four examples to the kernel sample directory.

It shows how to handle:
- a byte stream fifo
- a integer type fifo
- a dynamic record sized fifo
- the fifo DMA functions

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
 samples/Kconfig                    |   10 ++
 samples/Makefile                   |    2 +-
 samples/kfifo/Makefile             |    1 +
 samples/kfifo/bytestream-example.c |  163 +++++++++++++++++++++++++++++++++++
 samples/kfifo/dma-example.c        |  115 +++++++++++++++++++++++++
 samples/kfifo/inttype-example.c    |  157 +++++++++++++++++++++++++++++++++
 samples/kfifo/record-example.c     |  167 ++++++++++++++++++++++++++++++++++++
 7 files changed, 614 insertions(+), 1 deletions(-)
 create mode 100644 samples/kfifo/Makefile
 create mode 100644 samples/kfifo/bytestream-example.c
 create mode 100644 samples/kfifo/dma-example.c
 create mode 100644 samples/kfifo/inttype-example.c
 create mode 100644 samples/kfifo/record-example.c

diff --git a/samples/Kconfig b/samples/Kconfig
index 8924f72..954a1d5 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -44,4 +44,14 @@ config SAMPLE_HW_BREAKPOINT
 	help
 	  This builds kernel hardware breakpoint example modules.
 
+config SAMPLE_KFIFO
+	tristate "Build kfifo examples -- loadable modules only"
+	depends on m
+	help
+	  This config option will allow you to build a number of
+	  different kfifo sample modules showing how to use the
+	  generic kfifo API.
+
+	  If in doubt, say "N" here.
+
 endif # SAMPLES
diff --git a/samples/Makefile b/samples/Makefile
index 0f15e6d..76b3c34 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,4 +1,4 @@
 # Makefile for Linux samples code
 
 obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ tracepoints/ trace_events/ \
-			   hw_breakpoint/
+			   hw_breakpoint/ kfifo/
diff --git a/samples/kfifo/Makefile b/samples/kfifo/Makefile
new file mode 100644
index 0000000..bcc9484
--- /dev/null
+++ b/samples/kfifo/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SAMPLE_KFIFO) += bytestream-example.o dma-example.o inttype-example.o record-example.o
diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c
new file mode 100644
index 0000000..642eef3
--- /dev/null
+++ b/samples/kfifo/bytestream-example.c
@@ -0,0 +1,163 @@
+/*
+ * Sample kfifo byte stream implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a byte stream fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"bytestream-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static struct kfifo test;
+#else
+static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	unsigned char	buf[6];
+	unsigned char	i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "byte stream fifo test start\n");
+
+	/* put string into the fifo */
+	kfifo_in(&test, "hello", 5);
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 5 bytes from the fifo */
+	i = kfifo_out(&test, buf, 5);
+	printk(KERN_INFO "buf: %.*s\n", i, buf);
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	/* put values into the fifo until is full */
+	for (i = 20; kfifo_put(&test, &i); i++)
+		;
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
new file mode 100644
index 0000000..4ef4749
--- /dev/null
+++ b/samples/kfifo/dma-example.c
@@ -0,0 +1,115 @@
+/*
+ * Sample fifo dma implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to handle fifo dma operations.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+static struct kfifo fifo;
+
+static int __init example_init(void)
+{
+	int 			i;
+	unsigned int 		ret;
+	struct scatterlist	sg[10];
+
+	printk(KERN_INFO "DMA fifo test start\n");
+
+	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return 1;
+	}
+
+	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
+
+	kfifo_in(&fifo, "test", 4);
+
+	for (i = 0; i != 9; i++)
+		kfifo_put(&fifo, &i);
+
+	/* kick away first byte */
+	ret = kfifo_get(&fifo, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, fifo is full and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for receive:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: zero bytes received */
+		ret = 0;
+
+		/* finish the dma operation and update the received data */
+		kfifo_dma_in_finish(&fifo, ret);
+	}
+
+	ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, no data was available and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for transmit:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: 5 bytes transmitted */
+		ret = 5;
+
+		/* finish the dma operation and update the transmitted data */
+		kfifo_dma_out_finish(&fifo, ret);
+	}
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c
new file mode 100644
index 0000000..d6c5b7d
--- /dev/null
+++ b/samples/kfifo/inttype-example.c
@@ -0,0 +1,157 @@
+/*
+ * Sample kfifo int type implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a int type fifo.
+ */
+
+/* fifo size in elements (ints) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"int-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static DECLARE_KFIFO_PTR(test, int);
+#else
+static DEFINE_KFIFO(test, int, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	int		buf[6];
+	int		i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "int fifo test start\n");
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	for (i = 20; i != 30; i++)
+		kfifo_put(&test, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* show the first value without removing from the fifo */
+	if (kfifo_peek(&test, &i))
+		printk(KERN_INFO "%d\n", i);
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c
new file mode 100644
index 0000000..32c6e0b
--- /dev/null
+++ b/samples/kfifo/record-example.c
@@ -0,0 +1,167 @@
+/*
+ * Sample dynamic sized record fifo implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a variable sized record fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	128
+
+/* name of the proc entry */
+#define	PROC_FIFO	"record-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+/*
+ * struct kfifo_rec_ptr_1 and  STRUCT_KFIFO_REC_1 can handle records of a
+ * length between 0 and 255 bytes.
+ *
+ * struct kfifo_rec_ptr_2 and  STRUCT_KFIFO_REC_2 can handle records of a
+ * length between 0 and 65535 bytes.
+ */
+
+#ifdef DYNAMIC
+struct kfifo_rec_ptr_1 test;
+
+#else
+typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
+
+static mytest test;
+#endif
+
+static int __init testfunc(void)
+{
+	char		buf[100];
+	unsigned int	i;
+	unsigned int	ret;
+	struct { unsigned char buf[6]; } hello = { "hello" };
+
+	printk(KERN_INFO "record fifo test start\n");
+
+	kfifo_in(&test, &hello, sizeof(hello));
+
+	/* show the size of the next record in the fifo */
+	printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test));
+
+	/* put in variable length data */
+	for (i = 0; i < 10; i++) {
+		memset(buf, 'a' + i, i + 1);
+		kfifo_in(&test, buf, i + 1);
+	}
+
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* show the first record without removing from the fifo */
+	ret = kfifo_out_peek(&test, buf, sizeof(buf));
+	if (ret)
+		printk(KERN_INFO "%.*s\n", ret, buf);
+
+	/* print out all records in the fifo */
+	while (!kfifo_is_empty(&test)) {
+		ret = kfifo_out(&test, buf, sizeof(buf));
+		printk(KERN_INFO "%.*s\n", ret, buf);
+	}
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
-- 
1.7.2

[PATCH 4/4] add example files to the kernel sample directory

[stefani]

From: Stefani Seibold <stefani@seibold.net>

This patch add four examples to the kernel sample directory.

It shows how to handle:
- a byte stream fifo
- a integer type fifo
- a dynamic record sized fifo
- the fifo DMA functions

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
 samples/Kconfig                    |   10 ++
 samples/Makefile                   |    2 +-
 samples/kfifo/Makefile             |    1 +
 samples/kfifo/bytestream-example.c |  163 +++++++++++++++++++++++++++++++++++
 samples/kfifo/dma-example.c        |  115 +++++++++++++++++++++++++
 samples/kfifo/inttype-example.c    |  157 +++++++++++++++++++++++++++++++++
 samples/kfifo/record-example.c     |  167 ++++++++++++++++++++++++++++++++++++
 7 files changed, 614 insertions(+), 1 deletions(-)
 create mode 100644 samples/kfifo/Makefile
 create mode 100644 samples/kfifo/bytestream-example.c
 create mode 100644 samples/kfifo/dma-example.c
 create mode 100644 samples/kfifo/inttype-example.c
 create mode 100644 samples/kfifo/record-example.c

diff --git a/samples/Kconfig b/samples/Kconfig
index 8924f72..954a1d5 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -44,4 +44,14 @@ config SAMPLE_HW_BREAKPOINT
 	help
 	  This builds kernel hardware breakpoint example modules.
 
+config SAMPLE_KFIFO
+	tristate "Build kfifo examples -- loadable modules only"
+	depends on m
+	help
+	  This config option will allow you to build a number of
+	  different kfifo sample modules showing how to use the
+	  generic kfifo API.
+
+	  If in doubt, say "N" here.
+
 endif # SAMPLES
diff --git a/samples/Makefile b/samples/Makefile
index 0f15e6d..76b3c34 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,4 +1,4 @@
 # Makefile for Linux samples code
 
 obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ tracepoints/ trace_events/ \
-			   hw_breakpoint/
+			   hw_breakpoint/ kfifo/
diff --git a/samples/kfifo/Makefile b/samples/kfifo/Makefile
new file mode 100644
index 0000000..bcc9484
--- /dev/null
+++ b/samples/kfifo/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SAMPLE_KFIFO) += bytestream-example.o dma-example.o inttype-example.o record-example.o
diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c
new file mode 100644
index 0000000..642eef3
--- /dev/null
+++ b/samples/kfifo/bytestream-example.c
@@ -0,0 +1,163 @@
+/*
+ * Sample kfifo byte stream implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a byte stream fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"bytestream-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static struct kfifo test;
+#else
+static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	unsigned char	buf[6];
+	unsigned char	i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "byte stream fifo test start\n");
+
+	/* put string into the fifo */
+	kfifo_in(&test, "hello", 5);
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 5 bytes from the fifo */
+	i = kfifo_out(&test, buf, 5);
+	printk(KERN_INFO "buf: %.*s\n", i, buf);
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	/* put values into the fifo until is full */
+	for (i = 20; kfifo_put(&test, &i); i++)
+		;
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
new file mode 100644
index 0000000..4ef4749
--- /dev/null
+++ b/samples/kfifo/dma-example.c
@@ -0,0 +1,115 @@
+/*
+ * Sample fifo dma implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to handle fifo dma operations.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+static struct kfifo fifo;
+
+static int __init example_init(void)
+{
+	int 			i;
+	unsigned int 		ret;
+	struct scatterlist	sg[10];
+
+	printk(KERN_INFO "DMA fifo test start\n");
+
+	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return 1;
+	}
+
+	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
+
+	kfifo_in(&fifo, "test", 4);
+
+	for (i = 0; i != 9; i++)
+		kfifo_put(&fifo, &i);
+
+	/* kick away first byte */
+	ret = kfifo_get(&fifo, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, fifo is full and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for receive:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: zero bytes received */
+		ret = 0;
+
+		/* finish the dma operation and update the received data */
+		kfifo_dma_in_finish(&fifo, ret);
+	}
+
+	ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, no data was available and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for transmit:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: 5 bytes transmitted */
+		ret = 5;
+
+		/* finish the dma operation and update the transmitted data */
+		kfifo_dma_out_finish(&fifo, ret);
+	}
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c
new file mode 100644
index 0000000..d6c5b7d
--- /dev/null
+++ b/samples/kfifo/inttype-example.c
@@ -0,0 +1,157 @@
+/*
+ * Sample kfifo int type implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a int type fifo.
+ */
+
+/* fifo size in elements (ints) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"int-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static DECLARE_KFIFO_PTR(test, int);
+#else
+static DEFINE_KFIFO(test, int, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	int		buf[6];
+	int		i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "int fifo test start\n");
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	for (i = 20; i != 30; i++)
+		kfifo_put(&test, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* show the first value without removing from the fifo */
+	if (kfifo_peek(&test, &i))
+		printk(KERN_INFO "%d\n", i);
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c
new file mode 100644
index 0000000..32c6e0b
--- /dev/null
+++ b/samples/kfifo/record-example.c
@@ -0,0 +1,167 @@
+/*
+ * Sample dynamic sized record fifo implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a variable sized record fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	128
+
+/* name of the proc entry */
+#define	PROC_FIFO	"record-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+/*
+ * struct kfifo_rec_ptr_1 and  STRUCT_KFIFO_REC_1 can handle records of a
+ * length between 0 and 255 bytes.
+ *
+ * struct kfifo_rec_ptr_2 and  STRUCT_KFIFO_REC_2 can handle records of a
+ * length between 0 and 65535 bytes.
+ */
+
+#ifdef DYNAMIC
+struct kfifo_rec_ptr_1 test;
+
+#else
+typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
+
+static mytest test;
+#endif
+
+static int __init testfunc(void)
+{
+	char		buf[100];
+	unsigned int	i;
+	unsigned int	ret;
+	struct { unsigned char buf[6]; } hello = { "hello" };
+
+	printk(KERN_INFO "record fifo test start\n");
+
+	kfifo_in(&test, &hello, sizeof(hello));
+
+	/* show the size of the next record in the fifo */
+	printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test));
+
+	/* put in variable length data */
+	for (i = 0; i < 10; i++) {
+		memset(buf, 'a' + i, i + 1);
+		kfifo_in(&test, buf, i + 1);
+	}
+
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* show the first record without removing from the fifo */
+	ret = kfifo_out_peek(&test, buf, sizeof(buf));
+	if (ret)
+		printk(KERN_INFO "%.*s\n", ret, buf);
+
+	/* print out all records in the fifo */
+	while (!kfifo_is_empty(&test)) {
+		ret = kfifo_out(&test, buf, sizeof(buf));
+		printk(KERN_INFO "%.*s\n", ret, buf);
+	}
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
-- 
1.7.1.1

[PATCH 4/4] add example files to the kernel sample directory

[stefani]

From: Stefani Seibold <stefani@seibold.net>

This patch add four examples to the kernel sample directory.

It shows how to handle:
- a byte stream fifo
- a integer type fifo
- a dynamic record sized fifo
- the fifo DMA functions

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
 samples/Kconfig                    |   10 ++
 samples/Makefile                   |    2 +-
 samples/kfifo/Makefile             |    1 +
 samples/kfifo/bytestream-example.c |  163 +++++++++++++++++++++++++++++++++++
 samples/kfifo/dma-example.c        |  115 +++++++++++++++++++++++++
 samples/kfifo/inttype-example.c    |  157 +++++++++++++++++++++++++++++++++
 samples/kfifo/record-example.c     |  167 ++++++++++++++++++++++++++++++++++++
 7 files changed, 614 insertions(+), 1 deletions(-)
 create mode 100644 samples/kfifo/Makefile
 create mode 100644 samples/kfifo/bytestream-example.c
 create mode 100644 samples/kfifo/dma-example.c
 create mode 100644 samples/kfifo/inttype-example.c
 create mode 100644 samples/kfifo/record-example.c

diff --git a/samples/Kconfig b/samples/Kconfig
index 8924f72..954a1d5 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -44,4 +44,14 @@ config SAMPLE_HW_BREAKPOINT
 	help
 	  This builds kernel hardware breakpoint example modules.
 
+config SAMPLE_KFIFO
+	tristate "Build kfifo examples -- loadable modules only"
+	depends on m
+	help
+	  This config option will allow you to build a number of
+	  different kfifo sample modules showing how to use the
+	  generic kfifo API.
+
+	  If in doubt, say "N" here.
+
 endif # SAMPLES
diff --git a/samples/Makefile b/samples/Makefile
index 0f15e6d..76b3c34 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,4 +1,4 @@
 # Makefile for Linux samples code
 
 obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ tracepoints/ trace_events/ \
-			   hw_breakpoint/
+			   hw_breakpoint/ kfifo/
diff --git a/samples/kfifo/Makefile b/samples/kfifo/Makefile
new file mode 100644
index 0000000..bcc9484
--- /dev/null
+++ b/samples/kfifo/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SAMPLE_KFIFO) += bytestream-example.o dma-example.o inttype-example.o record-example.o
diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c
new file mode 100644
index 0000000..642eef3
--- /dev/null
+++ b/samples/kfifo/bytestream-example.c
@@ -0,0 +1,163 @@
+/*
+ * Sample kfifo byte stream implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a byte stream fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"bytestream-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static struct kfifo test;
+#else
+static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	unsigned char	buf[6];
+	unsigned char	i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "byte stream fifo test start\n");
+
+	/* put string into the fifo */
+	kfifo_in(&test, "hello", 5);
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 5 bytes from the fifo */
+	i = kfifo_out(&test, buf, 5);
+	printk(KERN_INFO "buf: %.*s\n", i, buf);
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	/* put values into the fifo until is full */
+	for (i = 20; kfifo_put(&test, &i); i++)
+		;
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
new file mode 100644
index 0000000..4ef4749
--- /dev/null
+++ b/samples/kfifo/dma-example.c
@@ -0,0 +1,115 @@
+/*
+ * Sample fifo dma implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to handle fifo dma operations.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+static struct kfifo fifo;
+
+static int __init example_init(void)
+{
+	int 			i;
+	unsigned int 		ret;
+	struct scatterlist	sg[10];
+
+	printk(KERN_INFO "DMA fifo test start\n");
+
+	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return 1;
+	}
+
+	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
+
+	kfifo_in(&fifo, "test", 4);
+
+	for (i = 0; i != 9; i++)
+		kfifo_put(&fifo, &i);
+
+	/* kick away first byte */
+	ret = kfifo_get(&fifo, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, fifo is full and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for receive:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: zero bytes received */
+		ret = 0;
+
+		/* finish the dma operation and update the received data */
+		kfifo_dma_in_finish(&fifo, ret);
+	}
+
+	ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, no data was available and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for transmit:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: 5 bytes transmitted */
+		ret = 5;
+
+		/* finish the dma operation and update the transmitted data */
+		kfifo_dma_out_finish(&fifo, ret);
+	}
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c
new file mode 100644
index 0000000..d6c5b7d
--- /dev/null
+++ b/samples/kfifo/inttype-example.c
@@ -0,0 +1,157 @@
+/*
+ * Sample kfifo int type implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a int type fifo.
+ */
+
+/* fifo size in elements (ints) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"int-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static DECLARE_KFIFO_PTR(test, int);
+#else
+static DEFINE_KFIFO(test, int, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	int		buf[6];
+	int		i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "int fifo test start\n");
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	for (i = 20; i != 30; i++)
+		kfifo_put(&test, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* show the first value without removing from the fifo */
+	if (kfifo_peek(&test, &i))
+		printk(KERN_INFO "%d\n", i);
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c
new file mode 100644
index 0000000..32c6e0b
--- /dev/null
+++ b/samples/kfifo/record-example.c
@@ -0,0 +1,167 @@
+/*
+ * Sample dynamic sized record fifo implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a variable sized record fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	128
+
+/* name of the proc entry */
+#define	PROC_FIFO	"record-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+/*
+ * struct kfifo_rec_ptr_1 and  STRUCT_KFIFO_REC_1 can handle records of a
+ * length between 0 and 255 bytes.
+ *
+ * struct kfifo_rec_ptr_2 and  STRUCT_KFIFO_REC_2 can handle records of a
+ * length between 0 and 65535 bytes.
+ */
+
+#ifdef DYNAMIC
+struct kfifo_rec_ptr_1 test;
+
+#else
+typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
+
+static mytest test;
+#endif
+
+static int __init testfunc(void)
+{
+	char		buf[100];
+	unsigned int	i;
+	unsigned int	ret;
+	struct { unsigned char buf[6]; } hello = { "hello" };
+
+	printk(KERN_INFO "record fifo test start\n");
+
+	kfifo_in(&test, &hello, sizeof(hello));
+
+	/* show the size of the next record in the fifo */
+	printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test));
+
+	/* put in variable length data */
+	for (i = 0; i < 10; i++) {
+		memset(buf, 'a' + i, i + 1);
+		kfifo_in(&test, buf, i + 1);
+	}
+
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* show the first record without removing from the fifo */
+	ret = kfifo_out_peek(&test, buf, sizeof(buf));
+	if (ret)
+		printk(KERN_INFO "%.*s\n", ret, buf);
+
+	/* print out all records in the fifo */
+	while (!kfifo_is_empty(&test)) {
+		ret = kfifo_out(&test, buf, sizeof(buf));
+		printk(KERN_INFO "%.*s\n", ret, buf);
+	}
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
-- 
1.7.0.4

[PATCH 4/4] add example files to the kernel sample directory

[stefani]

From: Stefani Seibold <stefani@seibold.net>

This patch add four examples to the kernel sample directory.

It shows how to handle:
- a byte stream fifo
- a integer type fifo
- a dynamic record sized fifo
- the fifo DMA functions

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
 samples/Kconfig                    |   10 ++
 samples/Makefile                   |    2 +-
 samples/kfifo/Makefile             |    1 +
 samples/kfifo/bytestream-example.c |  163 +++++++++++++++++++++++++++++++++++
 samples/kfifo/dma-example.c        |  115 +++++++++++++++++++++++++
 samples/kfifo/inttype-example.c    |  157 +++++++++++++++++++++++++++++++++
 samples/kfifo/record-example.c     |  167 ++++++++++++++++++++++++++++++++++++
 7 files changed, 614 insertions(+), 1 deletions(-)
 create mode 100644 samples/kfifo/Makefile
 create mode 100644 samples/kfifo/bytestream-example.c
 create mode 100644 samples/kfifo/dma-example.c
 create mode 100644 samples/kfifo/inttype-example.c
 create mode 100644 samples/kfifo/record-example.c

diff --git a/samples/Kconfig b/samples/Kconfig
index 8924f72..954a1d5 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -44,4 +44,14 @@ config SAMPLE_HW_BREAKPOINT
 	help
 	  This builds kernel hardware breakpoint example modules.
 
+config SAMPLE_KFIFO
+	tristate "Build kfifo examples -- loadable modules only"
+	depends on m
+	help
+	  This config option will allow you to build a number of
+	  different kfifo sample modules showing how to use the
+	  generic kfifo API.
+
+	  If in doubt, say "N" here.
+
 endif # SAMPLES
diff --git a/samples/Makefile b/samples/Makefile
index 0f15e6d..76b3c34 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,4 +1,4 @@
 # Makefile for Linux samples code
 
 obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ tracepoints/ trace_events/ \
-			   hw_breakpoint/
+			   hw_breakpoint/ kfifo/
diff --git a/samples/kfifo/Makefile b/samples/kfifo/Makefile
new file mode 100644
index 0000000..bcc9484
--- /dev/null
+++ b/samples/kfifo/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SAMPLE_KFIFO) += bytestream-example.o dma-example.o inttype-example.o record-example.o
diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c
new file mode 100644
index 0000000..642eef3
--- /dev/null
+++ b/samples/kfifo/bytestream-example.c
@@ -0,0 +1,163 @@
+/*
+ * Sample kfifo byte stream implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a byte stream fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"bytestream-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static struct kfifo test;
+#else
+static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	unsigned char	buf[6];
+	unsigned char	i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "byte stream fifo test start\n");
+
+	/* put string into the fifo */
+	kfifo_in(&test, "hello", 5);
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 5 bytes from the fifo */
+	i = kfifo_out(&test, buf, 5);
+	printk(KERN_INFO "buf: %.*s\n", i, buf);
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	/* put values into the fifo until is full */
+	for (i = 20; kfifo_put(&test, &i); i++)
+		;
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
new file mode 100644
index 0000000..4ef4749
--- /dev/null
+++ b/samples/kfifo/dma-example.c
@@ -0,0 +1,115 @@
+/*
+ * Sample fifo dma implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to handle fifo dma operations.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+static struct kfifo fifo;
+
+static int __init example_init(void)
+{
+	int 			i;
+	unsigned int 		ret;
+	struct scatterlist	sg[10];
+
+	printk(KERN_INFO "DMA fifo test start\n");
+
+	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return 1;
+	}
+
+	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
+
+	kfifo_in(&fifo, "test", 4);
+
+	for (i = 0; i != 9; i++)
+		kfifo_put(&fifo, &i);
+
+	/* kick away first byte */
+	ret = kfifo_get(&fifo, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, fifo is full and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for receive:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: zero bytes received */
+		ret = 0;
+
+		/* finish the dma operation and update the received data */
+		kfifo_dma_in_finish(&fifo, ret);
+	}
+
+	ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, no data was available and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for transmit:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: 5 bytes transmitted */
+		ret = 5;
+
+		/* finish the dma operation and update the transmitted data */
+		kfifo_dma_out_finish(&fifo, ret);
+	}
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c
new file mode 100644
index 0000000..d6c5b7d
--- /dev/null
+++ b/samples/kfifo/inttype-example.c
@@ -0,0 +1,157 @@
+/*
+ * Sample kfifo int type implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a int type fifo.
+ */
+
+/* fifo size in elements (ints) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"int-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static DECLARE_KFIFO_PTR(test, int);
+#else
+static DEFINE_KFIFO(test, int, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	int		buf[6];
+	int		i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "int fifo test start\n");
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	for (i = 20; i != 30; i++)
+		kfifo_put(&test, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* show the first value without removing from the fifo */
+	if (kfifo_peek(&test, &i))
+		printk(KERN_INFO "%d\n", i);
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c
new file mode 100644
index 0000000..32c6e0b
--- /dev/null
+++ b/samples/kfifo/record-example.c
@@ -0,0 +1,167 @@
+/*
+ * Sample dynamic sized record fifo implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a variable sized record fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	128
+
+/* name of the proc entry */
+#define	PROC_FIFO	"record-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+/*
+ * struct kfifo_rec_ptr_1 and  STRUCT_KFIFO_REC_1 can handle records of a
+ * length between 0 and 255 bytes.
+ *
+ * struct kfifo_rec_ptr_2 and  STRUCT_KFIFO_REC_2 can handle records of a
+ * length between 0 and 65535 bytes.
+ */
+
+#ifdef DYNAMIC
+struct kfifo_rec_ptr_1 test;
+
+#else
+typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
+
+static mytest test;
+#endif
+
+static int __init testfunc(void)
+{
+	char		buf[100];
+	unsigned int	i;
+	unsigned int	ret;
+	struct { unsigned char buf[6]; } hello = { "hello" };
+
+	printk(KERN_INFO "record fifo test start\n");
+
+	kfifo_in(&test, &hello, sizeof(hello));
+
+	/* show the size of the next record in the fifo */
+	printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test));
+
+	/* put in variable length data */
+	for (i = 0; i < 10; i++) {
+		memset(buf, 'a' + i, i + 1);
+		kfifo_in(&test, buf, i + 1);
+	}
+
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* show the first record without removing from the fifo */
+	ret = kfifo_out_peek(&test, buf, sizeof(buf));
+	if (ret)
+		printk(KERN_INFO "%.*s\n", ret, buf);
+
+	/* print out all records in the fifo */
+	while (!kfifo_is_empty(&test)) {
+		ret = kfifo_out(&test, buf, sizeof(buf));
+		printk(KERN_INFO "%.*s\n", ret, buf);
+	}
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
-- 
1.7.0.4

[PATCH 4/4] add example files to the kernel sample directory

[stefani]

From: Stefani Seibold <stefani@seibold.net>

This patch add four examples to the kernel sample directory.

It shows how to handle:
- a byte stream fifo
- a integer type fifo
- a dynamic record sized fifo
- the fifo DMA functions

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
 samples/Kconfig                    |   10 ++
 samples/Makefile                   |    2 +-
 samples/kfifo/Makefile             |    1 +
 samples/kfifo/bytestream-example.c |  163 +++++++++++++++++++++++++++++++++++
 samples/kfifo/dma-example.c        |  115 +++++++++++++++++++++++++
 samples/kfifo/inttype-example.c    |  157 +++++++++++++++++++++++++++++++++
 samples/kfifo/record-example.c     |  167 ++++++++++++++++++++++++++++++++++++
 7 files changed, 614 insertions(+), 1 deletions(-)
 create mode 100644 samples/kfifo/Makefile
 create mode 100644 samples/kfifo/bytestream-example.c
 create mode 100644 samples/kfifo/dma-example.c
 create mode 100644 samples/kfifo/inttype-example.c
 create mode 100644 samples/kfifo/record-example.c

diff --git a/samples/Kconfig b/samples/Kconfig
index 8924f72..954a1d5 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -44,4 +44,14 @@ config SAMPLE_HW_BREAKPOINT
 	help
 	  This builds kernel hardware breakpoint example modules.
 
+config SAMPLE_KFIFO
+	tristate "Build kfifo examples -- loadable modules only"
+	depends on m
+	help
+	  This config option will allow you to build a number of
+	  different kfifo sample modules showing how to use the
+	  generic kfifo API.
+
+	  If in doubt, say "N" here.
+
 endif # SAMPLES
diff --git a/samples/Makefile b/samples/Makefile
index 0f15e6d..76b3c34 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,4 +1,4 @@
 # Makefile for Linux samples code
 
 obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ tracepoints/ trace_events/ \
-			   hw_breakpoint/
+			   hw_breakpoint/ kfifo/
diff --git a/samples/kfifo/Makefile b/samples/kfifo/Makefile
new file mode 100644
index 0000000..bcc9484
--- /dev/null
+++ b/samples/kfifo/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SAMPLE_KFIFO) += bytestream-example.o dma-example.o inttype-example.o record-example.o
diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c
new file mode 100644
index 0000000..642eef3
--- /dev/null
+++ b/samples/kfifo/bytestream-example.c
@@ -0,0 +1,163 @@
+/*
+ * Sample kfifo byte stream implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a byte stream fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"bytestream-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static struct kfifo test;
+#else
+static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	unsigned char	buf[6];
+	unsigned char	i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "byte stream fifo test start\n");
+
+	/* put string into the fifo */
+	kfifo_in(&test, "hello", 5);
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 5 bytes from the fifo */
+	i = kfifo_out(&test, buf, 5);
+	printk(KERN_INFO "buf: %.*s\n", i, buf);
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	/* put values into the fifo until is full */
+	for (i = 20; kfifo_put(&test, &i); i++)
+		;
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/dma-example.c b/samples/kfifo/dma-example.c
new file mode 100644
index 0000000..4ef4749
--- /dev/null
+++ b/samples/kfifo/dma-example.c
@@ -0,0 +1,115 @@
+/*
+ * Sample fifo dma implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to handle fifo dma operations.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+static struct kfifo fifo;
+
+static int __init example_init(void)
+{
+	int 			i;
+	unsigned int 		ret;
+	struct scatterlist	sg[10];
+
+	printk(KERN_INFO "DMA fifo test start\n");
+
+	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return 1;
+	}
+
+	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
+
+	kfifo_in(&fifo, "test", 4);
+
+	for (i = 0; i != 9; i++)
+		kfifo_put(&fifo, &i);
+
+	/* kick away first byte */
+	ret = kfifo_get(&fifo, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, fifo is full and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for receive:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: zero bytes received */
+		ret = 0;
+
+		/* finish the dma operation and update the received data */
+		kfifo_dma_in_finish(&fifo, ret);
+	}
+
+	ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, no data was available and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for transmit:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: 5 bytes transmitted */
+		ret = 5;
+
+		/* finish the dma operation and update the transmitted data */
+		kfifo_dma_out_finish(&fifo, ret);
+	}
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c
new file mode 100644
index 0000000..d6c5b7d
--- /dev/null
+++ b/samples/kfifo/inttype-example.c
@@ -0,0 +1,157 @@
+/*
+ * Sample kfifo int type implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a int type fifo.
+ */
+
+/* fifo size in elements (ints) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"int-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static DECLARE_KFIFO_PTR(test, int);
+#else
+static DEFINE_KFIFO(test, int, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	int		buf[6];
+	int		i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "int fifo test start\n");
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	for (i = 20; i != 30; i++)
+		kfifo_put(&test, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* show the first value without removing from the fifo */
+	if (kfifo_peek(&test, &i))
+		printk(KERN_INFO "%d\n", i);
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c
new file mode 100644
index 0000000..32c6e0b
--- /dev/null
+++ b/samples/kfifo/record-example.c
@@ -0,0 +1,167 @@
+/*
+ * Sample dynamic sized record fifo implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a variable sized record fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	128
+
+/* name of the proc entry */
+#define	PROC_FIFO	"record-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+/*
+ * struct kfifo_rec_ptr_1 and  STRUCT_KFIFO_REC_1 can handle records of a
+ * length between 0 and 255 bytes.
+ *
+ * struct kfifo_rec_ptr_2 and  STRUCT_KFIFO_REC_2 can handle records of a
+ * length between 0 and 65535 bytes.
+ */
+
+#ifdef DYNAMIC
+struct kfifo_rec_ptr_1 test;
+
+#else
+typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
+
+static mytest test;
+#endif
+
+static int __init testfunc(void)
+{
+	char		buf[100];
+	unsigned int	i;
+	unsigned int	ret;
+	struct { unsigned char buf[6]; } hello = { "hello" };
+
+	printk(KERN_INFO "record fifo test start\n");
+
+	kfifo_in(&test, &hello, sizeof(hello));
+
+	/* show the size of the next record in the fifo */
+	printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test));
+
+	/* put in variable length data */
+	for (i = 0; i < 10; i++) {
+		memset(buf, 'a' + i, i + 1);
+		kfifo_in(&test, buf, i + 1);
+	}
+
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* show the first record without removing from the fifo */
+	ret = kfifo_out_peek(&test, buf, sizeof(buf));
+	if (ret)
+		printk(KERN_INFO "%.*s\n", ret, buf);
+
+	/* print out all records in the fifo */
+	while (!kfifo_is_empty(&test)) {
+		ret = kfifo_out(&test, buf, sizeof(buf));
+		printk(KERN_INFO "%.*s\n", ret, buf);
+	}
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
-- 
1.7.0.4

Re: [PATCH 4/4] add example files to the kernel sample directory

[Stefani Seibold]

This patch add four examples to the kernel sample directory.

It shows how to handle:
- a byte stream fifo
- a integer type fifo
- a dynamic record sized fifo
- the fifo DMA functions

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
 Kconfig                    |   10 ++
 Makefile                   |    2 
 kfifo/Makefile             |    1 
 kfifo/bytestream-example.c |  163 +++++++++++++++++++++++++++++++++++++++++++
 kfifo/dma-example.c        |  115 ++++++++++++++++++++++++++++++
 kfifo/inttype-example.c    |  157 ++++++++++++++++++++++++++++++++++++++++++
 kfifo/record-example.c     |  167 +++++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 614 insertions(+), 1 deletion(-)

diff -u -N -r -p linux-2.6.33-rc7.orig/samples/Kconfig linux-2.6.33-rc7.new/samples/Kconfig
--- linux-2.6.33-rc7.orig/samples/Kconfig	2010-02-11 17:05:58.178434640 +0100
+++ linux-2.6.33-rc7.new/samples/Kconfig	2010-02-12 08:31:54.092732092 +0100
@@ -44,4 +44,14 @@ config SAMPLE_HW_BREAKPOINT
 	help
 	  This builds kernel hardware breakpoint example modules.
 
+config SAMPLE_KFIFO
+	tristate "Build kfifo examples -- loadable modules only"
+	depends on m
+	help
+	  This config option will allow you to build a number of
+	  different kfifo sample modules showing how to use the
+	  generic kfifo API.
+
+	  If in doubt, say "N" here.
+
 endif # SAMPLES
diff -u -N -r -p linux-2.6.33-rc7.orig/samples/kfifo/bytestream-example.c linux-2.6.33-rc7.new/samples/kfifo/bytestream-example.c
--- linux-2.6.33-rc7.orig/samples/kfifo/bytestream-example.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.33-rc7.new/samples/kfifo/bytestream-example.c	2010-02-12 08:32:18.250874734 +0100
@@ -0,0 +1,163 @@
+/*
+ * Sample kfifo byte stream implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a byte stream fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"bytestream-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static struct kfifo test;
+#else
+static DECLARE_KFIFO(test, unsigned char, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	unsigned char	buf[6];
+	unsigned char	i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "byte stream fifo test start\n");
+
+	/* put string into the fifo */
+	kfifo_in(&test, "hello", 5);
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 5 bytes from the fifo */
+	i = kfifo_out(&test, buf, 5);
+	printk(KERN_INFO "buf: %.*s\n", i, buf);
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	/* put values into the fifo until is full */
+	for (i = 20; kfifo_put(&test, &i); i++)
+		;
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
Dateien linux-2.6.33-rc7.orig/samples/kfifo/.bytestream-example.c.swp und linux-2.6.33-rc7.new/samples/kfifo/.bytestream-example.c.swp sind verschieden.
diff -u -N -r -p linux-2.6.33-rc7.orig/samples/kfifo/dma-example.c linux-2.6.33-rc7.new/samples/kfifo/dma-example.c
--- linux-2.6.33-rc7.orig/samples/kfifo/dma-example.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.33-rc7.new/samples/kfifo/dma-example.c	2010-02-12 08:32:18.252420182 +0100
@@ -0,0 +1,115 @@
+/*
+ * Sample fifo dma implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to handle fifo dma operations.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	32
+
+static struct kfifo fifo;
+
+static int __init example_init(void)
+{
+	int 			i;
+	unsigned int 		ret;
+	struct scatterlist	sg[10];
+
+	printk(KERN_INFO "DMA fifo test start\n");
+
+	if (kfifo_alloc(&fifo, FIFO_SIZE, GFP_KERNEL)) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return 1;
+	}
+
+	printk(KERN_INFO "queue size: %u\n", kfifo_size(&fifo));
+
+	kfifo_in(&fifo, "test", 4);
+
+	for (i = 0; i != 9; i++)
+		kfifo_put(&fifo, &i);
+
+	/* kick away first byte */
+	ret = kfifo_get(&fifo, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	ret = kfifo_dma_in_prepare(&fifo, sg, ARRAY_SIZE(sg), FIFO_SIZE);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, fifo is full and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for receive:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: zero bytes received */
+		ret = 0;
+
+		/* finish the dma operation and update the received data */
+		kfifo_dma_in_finish(&fifo, ret);
+	}
+
+	ret = kfifo_dma_out_prepare(&fifo, sg, ARRAY_SIZE(sg), 8);
+	printk(KERN_INFO "DMA sgl entries: %d\n", ret);
+
+	/* if 0 was returned, no data was available and no sgl was created */
+	if (ret) {
+		printk(KERN_INFO "scatterlist for transmit:\n");
+		for (i = 0; i < ARRAY_SIZE(sg); i++) {
+			printk(KERN_INFO
+			"sg[%d] -> "
+			"page_link 0x%.8lx offset 0x%.8x length 0x%.8x\n",
+				i, sg[i].page_link, sg[i].offset, sg[i].length);
+
+			if (sg_is_last(&sg[i]))
+				break;
+		}
+
+		/* but here your code to setup and exectute the dma operation */
+		/* ... */
+
+		/* example: 5 bytes transmitted */
+		ret = 5;
+
+		/* finish the dma operation and update the transmitted data */
+		kfifo_dma_out_finish(&fifo, ret);
+	}
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&fifo));
+
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff -u -N -r -p linux-2.6.33-rc7.orig/samples/kfifo/inttype-example.c linux-2.6.33-rc7.new/samples/kfifo/inttype-example.c
--- linux-2.6.33-rc7.orig/samples/kfifo/inttype-example.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.33-rc7.new/samples/kfifo/inttype-example.c	2010-02-12 08:32:18.252420182 +0100
@@ -0,0 +1,157 @@
+/*
+ * Sample kfifo int type implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a int type fifo.
+ */
+
+/* fifo size in elements (ints) */
+#define FIFO_SIZE	32
+
+/* name of the proc entry */
+#define	PROC_FIFO	"int-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+#ifdef DYNAMIC
+static DECLARE_KFIFO_PTR(test, int);
+#else
+static DEFINE_KFIFO(test, int, FIFO_SIZE);
+#endif
+
+static int __init testfunc(void)
+{
+	int		buf[6];
+	int		i;
+	unsigned int	ret;
+
+	printk(KERN_INFO "int fifo test start\n");
+
+	/* put values into the fifo */
+	for (i = 0; i != 10; i++)
+		kfifo_put(&test, &i);
+
+	/* show the number of used elements */
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* get max of 2 elements from the fifo */
+	ret = kfifo_out(&test, buf, 2);
+	printk(KERN_INFO "ret: %d\n", ret);
+	/* and put it back to the end of the fifo */
+	ret = kfifo_in(&test, buf, ret);
+	printk(KERN_INFO "ret: %d\n", ret);
+
+	for (i = 20; i != 30; i++)
+		kfifo_put(&test, &i);
+
+	printk(KERN_INFO "queue len: %u\n", kfifo_len(&test));
+
+	/* show the first value without removing from the fifo */
+	if (kfifo_peek(&test, &i))
+		printk(KERN_INFO "%d\n", i);
+
+	/* print out all values in the fifo */
+	while (kfifo_get(&test, &i))
+		printk("%d ", i);
+	printk("\n");
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff -u -N -r -p linux-2.6.33-rc7.orig/samples/kfifo/Makefile linux-2.6.33-rc7.new/samples/kfifo/Makefile
--- linux-2.6.33-rc7.orig/samples/kfifo/Makefile	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.33-rc7.new/samples/kfifo/Makefile	2010-02-12 08:31:54.107750622 +0100
@@ -0,0 +1 @@
+obj-$(CONFIG_SAMPLE_KFIFO) += bytestream-example.o dma-example.o inttype-example.o record-example.o
diff -u -N -r -p linux-2.6.33-rc7.orig/samples/kfifo/record-example.c linux-2.6.33-rc7.new/samples/kfifo/record-example.c
--- linux-2.6.33-rc7.orig/samples/kfifo/record-example.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.33-rc7.new/samples/kfifo/record-example.c	2010-02-12 08:32:18.252420182 +0100
@@ -0,0 +1,167 @@
+/*
+ * Sample dynamic sized record fifo implementation
+ *
+ * Copyright (C) 2010 Stefani Seibold <stefani@seibold.net>
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/kfifo.h>
+
+/*
+ * This module shows how to create a variable sized record fifo.
+ */
+
+/* fifo size in elements (bytes) */
+#define FIFO_SIZE	128
+
+/* name of the proc entry */
+#define	PROC_FIFO	"record-fifo"
+
+/* lock for procfs read access */
+static DEFINE_MUTEX(read_lock);
+
+/* lock for procfs write access */
+static DEFINE_MUTEX(write_lock);
+
+/*
+ * define DYNAMIC in this example for a dynamically allocated fifo.
+ *
+ * Otherwise the fifo storage will be a part of the fifo structure.
+ */
+#if 0
+#define DYNAMIC
+#endif
+
+/*
+ * struct kfifo_rec_ptr_1 and  STRUCT_KFIFO_REC_1 can handle records of a
+ * length between 0 and 255 bytes.
+ *
+ * struct kfifo_rec_ptr_2 and  STRUCT_KFIFO_REC_2 can handle records of a
+ * length between 0 and 65535 bytes.
+ */
+
+#ifdef DYNAMIC
+struct kfifo_rec_ptr_1 test;
+
+#else
+typedef STRUCT_KFIFO_REC_1(FIFO_SIZE) mytest;
+
+static mytest test;
+#endif
+
+static int __init testfunc(void)
+{
+	char		buf[100];
+	unsigned int	i;
+	unsigned int	ret;
+	struct { unsigned char buf[6]; } hello = { "hello" };
+
+	printk(KERN_INFO "record fifo test start\n");
+
+	kfifo_in(&test, &hello, sizeof(hello));
+
+	/* show the size of the next record in the fifo */
+	printk(KERN_INFO "fifo peek len: %u\n", kfifo_peek_len(&test));
+
+	/* put in variable length data */
+	for (i = 0; i < 10; i++) {
+		memset(buf, 'a' + i, i + 1);
+		kfifo_in(&test, buf, i + 1);
+	}
+
+	printk(KERN_INFO "fifo len: %u\n", kfifo_len(&test));
+
+	/* show the first record without removing from the fifo */
+	ret = kfifo_out_peek(&test, buf, sizeof(buf));
+	if (ret)
+		printk(KERN_INFO "%.*s\n", ret, buf);
+
+	/* print out all records in the fifo */
+	while (!kfifo_is_empty(&test)) {
+		ret = kfifo_out(&test, buf, sizeof(buf));
+		printk(KERN_INFO "%.*s\n", ret, buf);
+	}
+
+	return 0;
+}
+
+static ssize_t fifo_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&write_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_from_user(&test, buf, count, &copied);
+
+	mutex_unlock(&write_lock);
+
+	return ret ? ret : copied;
+}
+
+static ssize_t fifo_read(struct file *file, char __user *buf,
+						size_t count, loff_t *ppos)
+{
+	int ret;
+	unsigned int copied;
+
+	if (mutex_lock_interruptible(&read_lock))
+		return -ERESTARTSYS;
+
+	ret = kfifo_to_user(&test, buf, count, &copied);
+
+	mutex_unlock(&read_lock);
+
+	return ret ? ret : copied;
+}
+
+static const struct file_operations fifo_fops = {
+	.owner		= THIS_MODULE,
+	.read		= fifo_read,
+	.write		= fifo_write,
+};
+
+static int __init example_init(void)
+{
+#ifdef DYNAMIC
+	int ret;
+
+	ret = kfifo_alloc(&test, FIFO_SIZE, GFP_KERNEL);
+	if (ret) {
+		printk(KERN_ERR "error kfifo_alloc\n");
+		return ret;
+	}
+#else
+	INIT_KFIFO(test);
+#endif
+	testfunc();
+
+	if (proc_create(PROC_FIFO, 0, NULL, &fifo_fops) == NULL) {
+#ifdef DYNAMIC
+		kfifo_free(&test);
+#endif
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+static void __exit example_exit(void)
+{
+	remove_proc_entry(PROC_FIFO, NULL);
+#ifdef DYNAMIC
+	kfifo_free(&test);
+#endif
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stefani Seibold <stefani@seibold.net>");
diff -u -N -r -p linux-2.6.33-rc7.orig/samples/Makefile linux-2.6.33-rc7.new/samples/Makefile
--- linux-2.6.33-rc7.orig/samples/Makefile	2010-02-11 17:05:58.178434640 +0100
+++ linux-2.6.33-rc7.new/samples/Makefile	2010-02-12 08:31:54.107750622 +0100
@@ -1,4 +1,4 @@
 # Makefile for Linux samples code
 
 obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ tracepoints/ trace_events/ \
-			   hw_breakpoint/
+			   hw_breakpoint/ kfifo/