[PATCH 1/8] staging:iio: Use iio_buffer_enabled instead of open coding it

[PATCH 1/8] staging:iio: Use iio_buffer_enabled instead of open coding it

[Lars-Peter Clausen]

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 drivers/staging/iio/industrialio-buffer.c |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/iio/industrialio-buffer.c b/drivers/staging/iio/industrialio-buffer.c
index a03a574..5fe7f83 100644
--- a/drivers/staging/iio/industrialio-buffer.c
+++ b/drivers/staging/iio/industrialio-buffer.c
@@ -420,7 +420,7 @@ ssize_t iio_buffer_store_enable(struct device *dev,
 	mutex_lock(&indio_dev->mlock);
 	previous_mode = indio_dev->currentmode;
 	requested_state = !(buf[0] == '0');
-	current_state = !!(previous_mode & INDIO_ALL_BUFFER_MODES);
+	current_state = iio_buffer_enabled(indio_dev);
 	if (current_state == requested_state) {
 		printk(KERN_INFO "iio-buffer, current state requested again\n");
 		goto done;
@@ -509,8 +509,7 @@ ssize_t iio_buffer_show_enable(struct device *dev,
 			       char *buf)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
-	return sprintf(buf, "%d\n", !!(indio_dev->currentmode
-				       & INDIO_ALL_BUFFER_MODES));
+	return sprintf(buf, "%d\n", iio_buffer_enabled(indio_dev));
 }
 EXPORT_SYMBOL(iio_buffer_show_enable);
 
-- 
1.7.7.3

[PATCH 2/8] staging:iio: Disallow changing scan elements in all buffered modes

[Lars-Peter Clausen]

Currently we only disallow changing the scan elements, while the buffer is
enabled, in triggered buffer mode. This patch changes it to disallow it for all
buffered modes. Disabling or enabling scan elements while the buffer is enabled
will cause undefined behavior since the reader will not be able to tell samples
with the new and old scan element set apart and thus wont be able to extract
any meaningful data from the buffer.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 drivers/staging/iio/industrialio-buffer.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/iio/industrialio-buffer.c b/drivers/staging/iio/industrialio-buffer.c
index 5fe7f83..91cb37a 100644
--- a/drivers/staging/iio/industrialio-buffer.c
+++ b/drivers/staging/iio/industrialio-buffer.c
@@ -153,7 +153,7 @@ static ssize_t iio_scan_el_store(struct device *dev,
 
 	state = !(buf[0] == '0');
 	mutex_lock(&indio_dev->mlock);
-	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
+	if (iio_buffer_enabled(indio_dev)) {
 		ret = -EBUSY;
 		goto error_ret;
 	}
@@ -196,7 +196,7 @@ static ssize_t iio_scan_el_ts_store(struct device *dev,
 
 	state = !(buf[0] == '0');
 	mutex_lock(&indio_dev->mlock);
-	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
+	if (iio_buffer_enabled(indio_dev)) {
 		ret = -EBUSY;
 		goto error_ret;
 	}
-- 
1.7.7.3

[PATCH 3/8] staging:iio: Disallow modifying buffer size when buffer is enabled

[Lars-Peter Clausen]

The buffer buffer storage is only update when enabling the buffer. Changing the
buffer size while the buffer is enabled will confuse the buffer in regard to
its actual buffer size and can cause potential memory corruption. Thus it is
only safe to modify the buffer size when the buffer is disabled.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 drivers/staging/iio/industrialio-buffer.c |   17 ++++++++++++-----
 1 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/iio/industrialio-buffer.c b/drivers/staging/iio/industrialio-buffer.c
index 91cb37a..9528026 100644
--- a/drivers/staging/iio/industrialio-buffer.c
+++ b/drivers/staging/iio/industrialio-buffer.c
@@ -396,13 +396,20 @@ ssize_t iio_buffer_write_length(struct device *dev,
 		if (val == buffer->access->get_length(buffer))
 			return len;
 
-	if (buffer->access->set_length) {
-		buffer->access->set_length(buffer, val);
-		if (buffer->access->mark_param_change)
-			buffer->access->mark_param_change(buffer);
+	mutex_lock(&indio_dev->mlock);
+	if (iio_buffer_enabled(indio_dev)) {
+		ret = -EBUSY;
+	} else {
+		if (buffer->access->set_length) {
+			buffer->access->set_length(buffer, val);
+			if (buffer->access->mark_param_change)
+				buffer->access->mark_param_change(buffer);
+		}
+		ret = 0;
 	}
+	mutex_unlock(&indio_dev->mlock);
 
-	return len;
+	return ret ? ret : len;
 }
 EXPORT_SYMBOL(iio_buffer_write_length);
 
-- 
1.7.7.3

[PATCH 4/8] staging:iio: Make sure a device is only opened once at a time

[Lars-Peter Clausen]

Our buffer implementation does not support multiple concurrent readers. So we
have to ensure that a device is only opened once at a time. So do the same thing
we do for the event fd and introduce a per device busy flag. The flag gets set
when opening the device and gets cleared when closing the device. If a open is
attempted while the busy flag is set we return -EBUSY.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 drivers/staging/iio/iio.h               |    3 +++
 drivers/staging/iio/industrialio-core.c |   17 ++++++++++++++---
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/iio/iio.h b/drivers/staging/iio/iio.h
index 6b57a79..3be99fd 100644
--- a/drivers/staging/iio/iio.h
+++ b/drivers/staging/iio/iio.h
@@ -318,6 +318,7 @@ struct iio_buffer_setup_ops {
  * @chrdev:		[INTERN] associated character device
  * @groups:		[INTERN] attribute groups
  * @groupcounter:	[INTERN] index of next attribute group
+ * @flags:		[INTERN] file ops related flags including busy flag.
  **/
 struct iio_dev {
 	int				id;
@@ -349,6 +350,8 @@ struct iio_dev {
 #define IIO_MAX_GROUPS 6
 	const struct attribute_group	*groups[IIO_MAX_GROUPS + 1];
 	int				groupcounter;
+
+	unsigned long			flags;
 };
 
 /**
diff --git a/drivers/staging/iio/industrialio-core.c b/drivers/staging/iio/industrialio-core.c
index 2eef85f..12d1576 100644
--- a/drivers/staging/iio/industrialio-core.c
+++ b/drivers/staging/iio/industrialio-core.c
@@ -1083,9 +1083,18 @@ static int iio_chrdev_open(struct inode *inode, struct file *filp)
 {
 	struct iio_dev *indio_dev = container_of(inode->i_cdev,
 						struct iio_dev, chrdev);
+	unsigned int ret;
+
+	if (test_and_set_bit(IIO_BUSY_BIT_POS, &indio_dev->flags))
+		return -EBUSY;
+
 	filp->private_data = indio_dev;
 
-	return iio_chrdev_buffer_open(indio_dev);
+	ret = iio_chrdev_buffer_open(indio_dev);
+	if (ret < 0)
+		clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
+
+	return ret;
 }
 
 /**
@@ -1093,8 +1102,10 @@ static int iio_chrdev_open(struct inode *inode, struct file *filp)
  **/
 static int iio_chrdev_release(struct inode *inode, struct file *filp)
 {
-	iio_chrdev_buffer_release(container_of(inode->i_cdev,
-					     struct iio_dev, chrdev));
+	struct iio_dev *indio_dev = container_of(inode->i_cdev,
+						struct iio_dev, chrdev);
+	iio_chrdev_buffer_release(indio_dev);
+	clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
 	return 0;
 }
 
-- 
1.7.7.3

[PATCH 5/8] staging:iio: Drop buffer busy flag

[Lars-Peter Clausen]

The flag is only cleared, never set or tested, so it is safe to remove it.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 drivers/staging/iio/buffer.h              |    2 --
 drivers/staging/iio/industrialio-buffer.c |    1 -
 2 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/iio/buffer.h b/drivers/staging/iio/buffer.h
index 44593b2..eb4938c 100644
--- a/drivers/staging/iio/buffer.h
+++ b/drivers/staging/iio/buffer.h
@@ -79,7 +79,6 @@ struct iio_buffer_access_funcs {
  *			created from the iio_chan_info array.
  * @pollq:		[INTERN] wait queue to allow for polling on the buffer.
  * @stufftoread:	[INTERN] flag to indicate new data.
- * @flags:		[INTERN] file ops related flags including busy flag.
  * @demux_list:		[INTERN] list of operations required to demux the scan.
  * @demux_bounce:	[INTERN] buffer for doing gather from incoming scan.
  **/
@@ -95,7 +94,6 @@ struct iio_buffer {
 	struct attribute_group			scan_el_group;
 	wait_queue_head_t			pollq;
 	bool					stufftoread;
-	unsigned long				flags;
 	const struct attribute_group *attrs;
 	struct list_head			demux_list;
 	unsigned char				*demux_bounce;
diff --git a/drivers/staging/iio/industrialio-buffer.c b/drivers/staging/iio/industrialio-buffer.c
index 9528026..f0a7044 100644
--- a/drivers/staging/iio/industrialio-buffer.c
+++ b/drivers/staging/iio/industrialio-buffer.c
@@ -80,7 +80,6 @@ void iio_chrdev_buffer_release(struct iio_dev *indio_dev)
 
 	if (!rb)
 		return;
-	clear_bit(IIO_BUSY_BIT_POS, &rb->flags);
 	if (rb->access->unmark_in_use)
 		rb->access->unmark_in_use(rb);
 }
-- 
1.7.7.3

[PATCH 6/8] staging:iio: Drop buffer mark_param_change callback

[Lars-Peter Clausen]

Right now we have a mark_param_change callback in the buffer access
functions struct, which should be called whenever the parameters (length,
bytes per datum) of the buffer change. But it is only called when the user
changes the buffer size, not when the bytes per datum change. Additionally each
buffer implementation already keeps track internally whether its parameters
have changed, making the call to mark_param_change after changing the buffer
length redundant. Since each buffer implementation knows best when one of its
parameters has changed just make tracking of this internal and drop the
mark_param_change callback.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 drivers/staging/iio/Documentation/ring.txt |    2 --
 drivers/staging/iio/buffer.h               |    4 ----
 drivers/staging/iio/industrialio-buffer.c  |    5 +----
 drivers/staging/iio/kfifo_buf.c            |   21 ++++++++++-----------
 drivers/staging/iio/ring_sw.c              |   21 ++++++++++-----------
 5 files changed, 21 insertions(+), 32 deletions(-)

diff --git a/drivers/staging/iio/Documentation/ring.txt b/drivers/staging/iio/Documentation/ring.txt
index 7e99ef2..5134fd9 100644
--- a/drivers/staging/iio/Documentation/ring.txt
+++ b/drivers/staging/iio/Documentation/ring.txt
@@ -39,8 +39,6 @@ rip_first_n
   The primary buffer reading function. Note that it may well not return
   as much data as requested.
 
-mark_param_changed
-  Used to indicate that something has changed. Used in conjunction with
 request_update
   If parameters have changed that require reinitialization or configuration of
   the buffer this will trigger it.
diff --git a/drivers/staging/iio/buffer.h b/drivers/staging/iio/buffer.h
index eb4938c..208c471 100644
--- a/drivers/staging/iio/buffer.h
+++ b/drivers/staging/iio/buffer.h
@@ -22,9 +22,6 @@ struct iio_buffer;
  * @unmark_in_use:	reduce reference count when no longer using buffer
  * @store_to:		actually store stuff to the buffer
  * @read_first_n:	try to get a specified number of bytes (must exist)
- * @mark_param_change:	notify buffer that some relevant parameter has changed
- *			Often this means the underlying storage may need to
- *			change.
  * @request_update:	if a parameter change has been marked, update underlying
  *			storage.
  * @get_bytes_per_datum:get current bytes per datum
@@ -51,7 +48,6 @@ struct iio_buffer_access_funcs {
 			    size_t n,
 			    char __user *buf);
 
-	int (*mark_param_change)(struct iio_buffer *buffer);
 	int (*request_update)(struct iio_buffer *buffer);
 
 	int (*get_bytes_per_datum)(struct iio_buffer *buffer);
diff --git a/drivers/staging/iio/industrialio-buffer.c b/drivers/staging/iio/industrialio-buffer.c
index f0a7044..adf6d35 100644
--- a/drivers/staging/iio/industrialio-buffer.c
+++ b/drivers/staging/iio/industrialio-buffer.c
@@ -399,11 +399,8 @@ ssize_t iio_buffer_write_length(struct device *dev,
 	if (iio_buffer_enabled(indio_dev)) {
 		ret = -EBUSY;
 	} else {
-		if (buffer->access->set_length) {
+		if (buffer->access->set_length)
 			buffer->access->set_length(buffer, val);
-			if (buffer->access->mark_param_change)
-				buffer->access->mark_param_change(buffer);
-		}
 		ret = 0;
 	}
 	mutex_unlock(&indio_dev->mlock);
diff --git a/drivers/staging/iio/kfifo_buf.c b/drivers/staging/iio/kfifo_buf.c
index b69cca5..33d9202 100644
--- a/drivers/staging/iio/kfifo_buf.c
+++ b/drivers/staging/iio/kfifo_buf.c
@@ -109,29 +109,29 @@ static int iio_get_bytes_per_datum_kfifo(struct iio_buffer *r)
 	return r->bytes_per_datum;
 }
 
+static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
+{
+	struct iio_kfifo *kf = iio_to_kfifo(r);
+	kf->update_needed = true;
+	return 0;
+}
+
 static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
 {
 	if (r->bytes_per_datum != bpd) {
 		r->bytes_per_datum = bpd;
-		if (r->access->mark_param_change)
-			r->access->mark_param_change(r);
+		iio_mark_update_needed_kfifo(r);
 	}
 	return 0;
 }
 
-static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
-{
-	struct iio_kfifo *kf = iio_to_kfifo(r);
-	kf->update_needed = true;
-	return 0;
-}
+
 
 static int iio_set_length_kfifo(struct iio_buffer *r, int length)
 {
 	if (r->length != length) {
 		r->length = length;
-		if (r->access->mark_param_change)
-			r->access->mark_param_change(r);
+		iio_mark_update_needed_kfifo(r);
 	}
 	return 0;
 }
@@ -174,7 +174,6 @@ const struct iio_buffer_access_funcs kfifo_access_funcs = {
 	.unmark_in_use = &iio_unmark_kfifo_in_use,
 	.store_to = &iio_store_to_kfifo,
 	.read_first_n = &iio_read_first_n_kfifo,
-	.mark_param_change = &iio_mark_update_needed_kfifo,
 	.request_update = &iio_request_update_kfifo,
 	.get_bytes_per_datum = &iio_get_bytes_per_datum_kfifo,
 	.set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
diff --git a/drivers/staging/iio/ring_sw.c b/drivers/staging/iio/ring_sw.c
index 4c15cc8..03eae3a 100644
--- a/drivers/staging/iio/ring_sw.c
+++ b/drivers/staging/iio/ring_sw.c
@@ -316,12 +316,18 @@ static int iio_get_bytes_per_datum_sw_rb(struct iio_buffer *r)
 	return ring->buf.bytes_per_datum;
 }
 
+static int iio_mark_update_needed_sw_rb(struct iio_buffer *r)
+{
+	struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r);
+	ring->update_needed = true;
+	return 0;
+}
+
 static int iio_set_bytes_per_datum_sw_rb(struct iio_buffer *r, size_t bpd)
 {
 	if (r->bytes_per_datum != bpd) {
 		r->bytes_per_datum = bpd;
-		if (r->access->mark_param_change)
-			r->access->mark_param_change(r);
+		iio_mark_update_needed_sw_rb(r);
 	}
 	return 0;
 }
@@ -335,18 +341,12 @@ static int iio_set_length_sw_rb(struct iio_buffer *r, int length)
 {
 	if (r->length != length) {
 		r->length = length;
-		if (r->access->mark_param_change)
-			r->access->mark_param_change(r);
+		iio_mark_update_needed_sw_rb(r);
 	}
 	return 0;
 }
 
-static int iio_mark_update_needed_sw_rb(struct iio_buffer *r)
-{
-	struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r);
-	ring->update_needed = true;
-	return 0;
-}
+
 
 static IIO_BUFFER_ENABLE_ATTR;
 static IIO_BUFFER_LENGTH_ATTR;
@@ -392,7 +392,6 @@ const struct iio_buffer_access_funcs ring_sw_access_funcs = {
 	.unmark_in_use = &iio_unmark_sw_rb_in_use,
 	.store_to = &iio_store_to_sw_rb,
 	.read_first_n = &iio_read_first_n_sw_rb,
-	.mark_param_change = &iio_mark_update_needed_sw_rb,
 	.request_update = &iio_request_update_sw_rb,
 	.get_bytes_per_datum = &iio_get_bytes_per_datum_sw_rb,
 	.set_bytes_per_datum = &iio_set_bytes_per_datum_sw_rb,
-- 
1.7.7.3

[PATCH 7/8] staging:iio: Drop the unused buffer enable() and is_enabled() callbacks

[Lars-Peter Clausen]

Currently none of the buffer implementations implements the enable() or
is_enable() nor does core code try to call these. So it is safe to remove them.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 drivers/staging/iio/Documentation/ring.txt |    4 ----
 drivers/staging/iio/buffer.h               |    5 -----
 2 files changed, 0 insertions(+), 9 deletions(-)

diff --git a/drivers/staging/iio/Documentation/ring.txt b/drivers/staging/iio/Documentation/ring.txt
index 5134fd9..0f21479 100644
--- a/drivers/staging/iio/Documentation/ring.txt
+++ b/drivers/staging/iio/Documentation/ring.txt
@@ -49,7 +49,3 @@ get_bytes_per_datum, set_bytes_per_datum
 get_length / set_length
   Get/set the number of complete scans that may be held by the buffer.
 
-is_enabled
-  Query if ring buffer is in use
-enable
-  Start the ring buffer.
diff --git a/drivers/staging/iio/buffer.h b/drivers/staging/iio/buffer.h
index 208c471..ea42b5d 100644
--- a/drivers/staging/iio/buffer.h
+++ b/drivers/staging/iio/buffer.h
@@ -28,8 +28,6 @@ struct iio_buffer;
  * @set_bytes_per_datum:set number of bytes per datum
  * @get_length:		get number of datums in buffer
  * @set_length:		set number of datums in buffer
- * @is_enabled:		query if buffer is currently being used
- * @enable:		enable the buffer
  *
  * The purpose of this structure is to make the buffer element
  * modular as event for a given driver, different usecases may require
@@ -54,9 +52,6 @@ struct iio_buffer_access_funcs {
 	int (*set_bytes_per_datum)(struct iio_buffer *buffer, size_t bpd);
 	int (*get_length)(struct iio_buffer *buffer);
 	int (*set_length)(struct iio_buffer *buffer, int length);
-
-	int (*is_enabled)(struct iio_buffer *buffer);
-	int (*enable)(struct iio_buffer *buffer);
 };
 
 /**
-- 
1.7.7.3

[PATCH 8/8] iio:staging: Drop {mark,unmark}_in_use callbacks

[Lars-Peter Clausen]

These callbacks are currently used by the individual buffer implementations to
ensure that the request_update callback is not issued while the buffer is in use.
But the core already provides sufficient measures to prevent this from happening
in the first place. So it is safe to remove them.

There is one functional change due to this patch. Since the buffer is no longer
marked as in use when the chrdev is opened, it is now possible to enable the
buffer while it is opened. This did not work before, because mark_param_change
did fail if the buffer was marked as in use.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 drivers/staging/iio/Documentation/ring.txt |    4 ---
 drivers/staging/iio/buffer.h               |    5 ----
 drivers/staging/iio/iio_core.h             |   11 --------
 drivers/staging/iio/industrialio-buffer.c  |   28 ----------------------
 drivers/staging/iio/industrialio-core.c    |    8 +-----
 drivers/staging/iio/kfifo_buf.c            |   32 -------------------------
 drivers/staging/iio/ring_sw.c              |   35 ----------------------------
 7 files changed, 1 insertions(+), 122 deletions(-)

diff --git a/drivers/staging/iio/Documentation/ring.txt b/drivers/staging/iio/Documentation/ring.txt
index 0f21479..e338077 100644
--- a/drivers/staging/iio/Documentation/ring.txt
+++ b/drivers/staging/iio/Documentation/ring.txt
@@ -23,10 +23,6 @@ The function pointers within here are used to allow the core to handle
 as much buffer functionality as possible. Note almost all of these
 are optional.
 
-mark_in_use, unmark_in_use
-  Basically indicate that not changes should be made to the buffer state that
-  will effect the form of the data being captures (e.g. scan elements or length)
-
 store_to
   If possible, push data to the buffer.
 
diff --git a/drivers/staging/iio/buffer.h b/drivers/staging/iio/buffer.h
index ea42b5d..6fb6e64 100644
--- a/drivers/staging/iio/buffer.h
+++ b/drivers/staging/iio/buffer.h
@@ -18,8 +18,6 @@ struct iio_buffer;
 
 /**
  * struct iio_buffer_access_funcs - access functions for buffers.
- * @mark_in_use:	reference counting, typically to prevent module removal
- * @unmark_in_use:	reduce reference count when no longer using buffer
  * @store_to:		actually store stuff to the buffer
  * @read_first_n:	try to get a specified number of bytes (must exist)
  * @request_update:	if a parameter change has been marked, update underlying
@@ -38,9 +36,6 @@ struct iio_buffer;
  * any of them not existing.
  **/
 struct iio_buffer_access_funcs {
-	void (*mark_in_use)(struct iio_buffer *buffer);
-	void (*unmark_in_use)(struct iio_buffer *buffer);
-
 	int (*store_to)(struct iio_buffer *buffer, u8 *data, s64 timestamp);
 	int (*read_first_n)(struct iio_buffer *buffer,
 			    size_t n,
diff --git a/drivers/staging/iio/iio_core.h b/drivers/staging/iio/iio_core.h
index ff27f13..107cfb1 100644
--- a/drivers/staging/iio/iio_core.h
+++ b/drivers/staging/iio/iio_core.h
@@ -33,9 +33,6 @@ int __iio_add_chan_devattr(const char *postfix,
 #ifdef CONFIG_IIO_BUFFER
 struct poll_table_struct;
 
-int iio_chrdev_buffer_open(struct iio_dev *indio_dev);
-void iio_chrdev_buffer_release(struct iio_dev *indio_dev);
-
 unsigned int iio_buffer_poll(struct file *filp,
 			     struct poll_table_struct *wait);
 ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
@@ -47,14 +44,6 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
 
 #else
 
-static inline int iio_chrdev_buffer_open(struct iio_dev *indio_dev)
-{
-	return 0;
-}
-
-static inline void iio_chrdev_buffer_release(struct iio_dev *indio_dev)
-{}
-
 #define iio_buffer_poll_addr NULL
 #define iio_buffer_read_first_n_outer_addr NULL
 
diff --git a/drivers/staging/iio/industrialio-buffer.c b/drivers/staging/iio/industrialio-buffer.c
index adf6d35..ed0a0ef 100644
--- a/drivers/staging/iio/industrialio-buffer.c
+++ b/drivers/staging/iio/industrialio-buffer.c
@@ -64,26 +64,6 @@ unsigned int iio_buffer_poll(struct file *filp,
 	return 0;
 }
 
-int iio_chrdev_buffer_open(struct iio_dev *indio_dev)
-{
-	struct iio_buffer *rb = indio_dev->buffer;
-	if (!rb)
-		return 0;
-	if (rb->access->mark_in_use)
-		rb->access->mark_in_use(rb);
-	return 0;
-}
-
-void iio_chrdev_buffer_release(struct iio_dev *indio_dev)
-{
-	struct iio_buffer *rb = indio_dev->buffer;
-
-	if (!rb)
-		return;
-	if (rb->access->unmark_in_use)
-		rb->access->unmark_in_use(rb);
-}
-
 void iio_buffer_init(struct iio_buffer *buffer)
 {
 	INIT_LIST_HEAD(&buffer->demux_list);
@@ -447,16 +427,12 @@ ssize_t iio_buffer_store_enable(struct device *dev,
 				goto error_ret;
 			}
 		}
-		if (buffer->access->mark_in_use)
-			buffer->access->mark_in_use(buffer);
 		/* Definitely possible for devices to support both of these.*/
 		if (indio_dev->modes & INDIO_BUFFER_TRIGGERED) {
 			if (!indio_dev->trig) {
 				printk(KERN_INFO
 				       "Buffer not started: no trigger\n");
 				ret = -EINVAL;
-				if (buffer->access->unmark_in_use)
-					buffer->access->unmark_in_use(buffer);
 				goto error_ret;
 			}
 			indio_dev->currentmode = INDIO_BUFFER_TRIGGERED;
@@ -473,8 +449,6 @@ ssize_t iio_buffer_store_enable(struct device *dev,
 				printk(KERN_INFO
 				       "Buffer not started:"
 				       "postenable failed\n");
-				if (buffer->access->unmark_in_use)
-					buffer->access->unmark_in_use(buffer);
 				indio_dev->currentmode = previous_mode;
 				if (indio_dev->setup_ops->postdisable)
 					indio_dev->setup_ops->
@@ -488,8 +462,6 @@ ssize_t iio_buffer_store_enable(struct device *dev,
 			if (ret)
 				goto error_ret;
 		}
-		if (buffer->access->unmark_in_use)
-			buffer->access->unmark_in_use(buffer);
 		indio_dev->currentmode = INDIO_DIRECT_MODE;
 		if (indio_dev->setup_ops->postdisable) {
 			ret = indio_dev->setup_ops->postdisable(indio_dev);
diff --git a/drivers/staging/iio/industrialio-core.c b/drivers/staging/iio/industrialio-core.c
index 12d1576..19f897f 100644
--- a/drivers/staging/iio/industrialio-core.c
+++ b/drivers/staging/iio/industrialio-core.c
@@ -1083,18 +1083,13 @@ static int iio_chrdev_open(struct inode *inode, struct file *filp)
 {
 	struct iio_dev *indio_dev = container_of(inode->i_cdev,
 						struct iio_dev, chrdev);
-	unsigned int ret;
 
 	if (test_and_set_bit(IIO_BUSY_BIT_POS, &indio_dev->flags))
 		return -EBUSY;
 
 	filp->private_data = indio_dev;
 
-	ret = iio_chrdev_buffer_open(indio_dev);
-	if (ret < 0)
-		clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
-
-	return ret;
+	return 0;
 }
 
 /**
@@ -1104,7 +1099,6 @@ static int iio_chrdev_release(struct inode *inode, struct file *filp)
 {
 	struct iio_dev *indio_dev = container_of(inode->i_cdev,
 						struct iio_dev, chrdev);
-	iio_chrdev_buffer_release(indio_dev);
 	clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
 	return 0;
 }
diff --git a/drivers/staging/iio/kfifo_buf.c b/drivers/staging/iio/kfifo_buf.c
index 33d9202..ff3e0c2 100644
--- a/drivers/staging/iio/kfifo_buf.c
+++ b/drivers/staging/iio/kfifo_buf.c
@@ -11,9 +11,7 @@
 struct iio_kfifo {
 	struct iio_buffer buffer;
 	struct kfifo kf;
-	int use_count;
 	int update_needed;
-	struct mutex use_lock;
 };
 
 #define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
@@ -33,47 +31,20 @@ static int iio_request_update_kfifo(struct iio_buffer *r)
 	int ret = 0;
 	struct iio_kfifo *buf = iio_to_kfifo(r);
 
-	mutex_lock(&buf->use_lock);
 	if (!buf->update_needed)
 		goto error_ret;
-	if (buf->use_count) {
-		ret = -EAGAIN;
-		goto error_ret;
-	}
 	kfifo_free(&buf->kf);
 	ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
 				   buf->buffer.length);
 error_ret:
-	mutex_unlock(&buf->use_lock);
 	return ret;
 }
 
-static void iio_mark_kfifo_in_use(struct iio_buffer *r)
-{
-	struct iio_kfifo *buf = iio_to_kfifo(r);
-	mutex_lock(&buf->use_lock);
-	buf->use_count++;
-	mutex_unlock(&buf->use_lock);
-}
-
-static void iio_unmark_kfifo_in_use(struct iio_buffer *r)
-{
-	struct iio_kfifo *buf = iio_to_kfifo(r);
-	mutex_lock(&buf->use_lock);
-	buf->use_count--;
-	mutex_unlock(&buf->use_lock);
-}
-
 static int iio_get_length_kfifo(struct iio_buffer *r)
 {
 	return r->length;
 }
 
-static inline void __iio_init_kfifo(struct iio_kfifo *kf)
-{
-	mutex_init(&kf->use_lock);
-}
-
 static IIO_BUFFER_ENABLE_ATTR;
 static IIO_BUFFER_LENGTH_ATTR;
 
@@ -98,7 +69,6 @@ struct iio_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
 	kf->update_needed = true;
 	iio_buffer_init(&kf->buffer);
 	kf->buffer.attrs = &iio_kfifo_attribute_group;
-	__iio_init_kfifo(kf);
 
 	return &kf->buffer;
 }
@@ -170,8 +140,6 @@ static int iio_read_first_n_kfifo(struct iio_buffer *r,
 }
 
 const struct iio_buffer_access_funcs kfifo_access_funcs = {
-	.mark_in_use = &iio_mark_kfifo_in_use,
-	.unmark_in_use = &iio_unmark_kfifo_in_use,
 	.store_to = &iio_store_to_kfifo,
 	.read_first_n = &iio_read_first_n_kfifo,
 	.request_update = &iio_request_update_kfifo,
diff --git a/drivers/staging/iio/ring_sw.c b/drivers/staging/iio/ring_sw.c
index 03eae3a..16f7dd5 100644
--- a/drivers/staging/iio/ring_sw.c
+++ b/drivers/staging/iio/ring_sw.c
@@ -24,9 +24,7 @@
  * @read_p:		read pointer (oldest available)
  * @write_p:		write pointer
  * @half_p:		half buffer length behind write_p (event generation)
- * @use_count:		reference count to prevent resizing when in use
  * @update_needed:	flag to indicated change in size requested
- * @use_lock:		lock to prevent change in size when in use
  *
  * Note that the first element of all ring buffers must be a
  * struct iio_buffer.
@@ -38,9 +36,7 @@ struct iio_sw_ring_buffer {
 	unsigned char		*write_p;
 	/* used to act as a point at which to signal an event */
 	unsigned char		*half_p;
-	int			use_count;
 	int			update_needed;
-	spinlock_t		use_lock;
 };
 
 #define iio_to_sw_ring(r) container_of(r, struct iio_sw_ring_buffer, buf)
@@ -58,33 +54,11 @@ static inline int __iio_allocate_sw_ring_buffer(struct iio_sw_ring_buffer *ring,
 	return ring->data ? 0 : -ENOMEM;
 }
 
-static inline void __iio_init_sw_ring_buffer(struct iio_sw_ring_buffer *ring)
-{
-	spin_lock_init(&ring->use_lock);
-}
-
 static inline void __iio_free_sw_ring_buffer(struct iio_sw_ring_buffer *ring)
 {
 	kfree(ring->data);
 }
 
-static void iio_mark_sw_rb_in_use(struct iio_buffer *r)
-{
-	struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r);
-	spin_lock(&ring->use_lock);
-	ring->use_count++;
-	spin_unlock(&ring->use_lock);
-}
-
-static void iio_unmark_sw_rb_in_use(struct iio_buffer *r)
-{
-	struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r);
-	spin_lock(&ring->use_lock);
-	ring->use_count--;
-	spin_unlock(&ring->use_lock);
-}
-
-
 /* Ring buffer related functionality */
 /* Store to ring is typically called in the bh of a data ready interrupt handler
  * in the device driver */
@@ -295,18 +269,12 @@ static int iio_request_update_sw_rb(struct iio_buffer *r)
 	struct iio_sw_ring_buffer *ring = iio_to_sw_ring(r);
 
 	r->stufftoread = false;
-	spin_lock(&ring->use_lock);
 	if (!ring->update_needed)
 		goto error_ret;
-	if (ring->use_count) {
-		ret = -EAGAIN;
-		goto error_ret;
-	}
 	__iio_free_sw_ring_buffer(ring);
 	ret = __iio_allocate_sw_ring_buffer(ring, ring->buf.bytes_per_datum,
 					    ring->buf.length);
 error_ret:
-	spin_unlock(&ring->use_lock);
 	return ret;
 }
 
@@ -374,7 +342,6 @@ struct iio_buffer *iio_sw_rb_allocate(struct iio_dev *indio_dev)
 	ring->update_needed = true;
 	buf = &ring->buf;
 	iio_buffer_init(buf);
-	__iio_init_sw_ring_buffer(ring);
 	buf->attrs = &iio_ring_attribute_group;
 
 	return buf;
@@ -388,8 +355,6 @@ void iio_sw_rb_free(struct iio_buffer *r)
 EXPORT_SYMBOL(iio_sw_rb_free);
 
 const struct iio_buffer_access_funcs ring_sw_access_funcs = {
-	.mark_in_use = &iio_mark_sw_rb_in_use,
-	.unmark_in_use = &iio_unmark_sw_rb_in_use,
 	.store_to = &iio_store_to_sw_rb,
 	.read_first_n = &iio_read_first_n_sw_rb,
 	.request_update = &iio_request_update_sw_rb,
-- 
1.7.7.3

Re: [PATCH 1/8] staging:iio: Use iio_buffer_enabled instead of open coding it

[Jonathan Cameron]

All this set look fine to me but please sit on them until Monday so they
can get a little more exposure.   Acked-by: Jonathan Cameron
<jic23@kernel.org> for all 8.
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

> ---
>  drivers/staging/iio/industrialio-buffer.c |    5 ++---
>  1 files changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/iio/industrialio-buffer.c b/drivers/staging/iio/industrialio-buffer.c
> index a03a574..5fe7f83 100644
> --- a/drivers/staging/iio/industrialio-buffer.c
> +++ b/drivers/staging/iio/industrialio-buffer.c
> @@ -420,7 +420,7 @@ ssize_t iio_buffer_store_enable(struct device *dev,
>  	mutex_lock(&indio_dev->mlock);
>  	previous_mode = indio_dev->currentmode;
>  	requested_state = !(buf[0] == '0');
> -	current_state = !!(previous_mode & INDIO_ALL_BUFFER_MODES);
> +	current_state = iio_buffer_enabled(indio_dev);
>  	if (current_state == requested_state) {
>  		printk(KERN_INFO "iio-buffer, current state requested again\n");
>  		goto done;
> @@ -509,8 +509,7 @@ ssize_t iio_buffer_show_enable(struct device *dev,
>  			       char *buf)
>  {
>  	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> -	return sprintf(buf, "%d\n", !!(indio_dev->currentmode
> -				       & INDIO_ALL_BUFFER_MODES));
> +	return sprintf(buf, "%d\n", iio_buffer_enabled(indio_dev));
>  }
>  EXPORT_SYMBOL(iio_buffer_show_enable);
>  

[PATCH 5/8] staging:iio: Drop buffer busy flag

[Lars-Peter Clausen]

The flag is only cleared, never set or tested, so it is safe to remove it.

Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 drivers/staging/iio/buffer.h              |    2 --
 drivers/staging/iio/industrialio-buffer.c |    1 -
 2 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/iio/buffer.h b/drivers/staging/iio/buffer.h
index 44593b2..eb4938c 100644
--- a/drivers/staging/iio/buffer.h
+++ b/drivers/staging/iio/buffer.h
@@ -79,7 +79,6 @@ struct iio_buffer_access_funcs {
  *			created from the iio_chan_info array.
  * @pollq:		[INTERN] wait queue to allow for polling on the buffer.
  * @stufftoread:	[INTERN] flag to indicate new data.
- * @flags:		[INTERN] file ops related flags including busy flag.
  * @demux_list:		[INTERN] list of operations required to demux the scan.
  * @demux_bounce:	[INTERN] buffer for doing gather from incoming scan.
  **/
@@ -95,7 +94,6 @@ struct iio_buffer {
 	struct attribute_group			scan_el_group;
 	wait_queue_head_t			pollq;
 	bool					stufftoread;
-	unsigned long				flags;
 	const struct attribute_group *attrs;
 	struct list_head			demux_list;
 	unsigned char				*demux_bounce;
diff --git a/drivers/staging/iio/industrialio-buffer.c b/drivers/staging/iio/industrialio-buffer.c
index 5947289..4c6d183 100644
--- a/drivers/staging/iio/industrialio-buffer.c
+++ b/drivers/staging/iio/industrialio-buffer.c
@@ -80,7 +80,6 @@ void iio_chrdev_buffer_release(struct iio_dev *indio_dev)
 
 	if (!rb)
 		return;
-	clear_bit(IIO_BUSY_BIT_POS, &rb->flags);
 	if (rb->access->unmark_in_use)
 		rb->access->unmark_in_use(rb);
 }
-- 
1.7.7.3