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* [RFC]Sample module for Kernel access to Ftrace instances.
@ 2019-09-20 23:59 Divya Indi
  2019-09-20 23:59 ` [PATCH] tracing: Sample module to demonstrate kernel " Divya Indi
  0 siblings, 1 reply; 4+ messages in thread
From: Divya Indi @ 2019-09-20 23:59 UTC (permalink / raw)
  To: Steven Rostedt, linux-kernel
  Cc: Divya Indi, Joe Jin, Srinivas Eeda, Aruna Ramakrishna, Manjunath Patil

[PATCH] tracing: Sample module to demonstrate kernel access to Ftrace

Hi,

This patch is for a sample module to demonstrate the use of APIs that 
were introduced/exported in order to access Ftrace instances from within the kernel.

Please Note: This module is dependent on -
- commit: f45d122 tracing: Kernel access to Ftrace instances
- Patches pending review: https://lore.kernel.org/lkml/1565805327-579-1-git-send-email-divya.indi@oracle.com/

The sample module creates/lookup a trace array called sample-instance on module load time. 
We then start a kernel thread(simple-thread) to -
1) Enable tracing for event "sample_event" to buffer associated with the trace array - "sample-instance".
2) Start a timer that will disable tracing to this buffer after 5 sec. (Tracing disabled after 5 sec ie at count=4)
3) Write to the buffer using trace_array_printk()
4) Stop the kernel thread and destroy the buffer during module unload.

A sample output for the same -

# tracer: nop
#
# entries-in-buffer/entries-written: 16/16   #P:4
#
#                              _-----=> irqs-off
#                             / _----=> need-resched
#                            | / _---=> hardirq/softirq
#                            || / _--=> preempt-depth
#                            ||| /     delay
#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
#              | |       |   ||||       |         |
 sample-instance-26797 [003] .... 955180.489833: simple_thread: trace_array_printk: count=0
 sample-instance-26797 [003] .... 955180.489836: sample_event: count value=0 at jiffies=5249940864
 sample-instance-26797 [003] .... 955181.513722: simple_thread: trace_array_printk: count=1
 sample-instance-26797 [003] .... 955181.513724: sample_event: count value=1 at jiffies=5249941888
 sample-instance-26797 [003] .... 955182.537629: simple_thread: trace_array_printk: count=2
 sample-instance-26797 [003] .... 955182.537631: sample_event: count value=2 at jiffies=5249942912
 sample-instance-26797 [003] .... 955183.561516: simple_thread: trace_array_printk: count=3
 sample-instance-26797 [003] .... 955183.561518: sample_event: count value=3 at jiffies=5249943936
 sample-instance-26797 [003] .... 955184.585423: simple_thread: trace_array_printk: count=4
 sample-instance-26797 [003] .... 955184.585427: sample_event: count value=4 at jiffies=5249944960
 sample-instance-26797 [003] .... 955185.609344: simple_thread: trace_array_printk: count=5
 sample-instance-26797 [003] .... 955186.633241: simple_thread: trace_array_printk: count=6
 sample-instance-26797 [003] .... 955187.657157: simple_thread: trace_array_printk: count=7
 sample-instance-26797 [003] .... 955188.681039: simple_thread: trace_array_printk: count=8
 sample-instance-26797 [003] .... 955189.704937: simple_thread: trace_array_printk: count=9
 sample-instance-26797 [003] .... 955190.728840: simple_thread: trace_array_printk: count=10

Let me know if you have any questions.

Thanks,
Divya

^ permalink raw reply	[flat|nested] 4+ messages in thread
* [PATCH] tracing: Sample module to demonstrate kernel access to Ftrace instances.
  2019-09-20 23:59 [RFC]Sample module for Kernel access to Ftrace instances Divya Indi
@ 2019-09-20 23:59 ` Divya Indi
  2019-10-15 17:05   ` Steven Rostedt
  0 siblings, 1 reply; 4+ messages in thread
From: Divya Indi @ 2019-09-20 23:59 UTC (permalink / raw)
  To: Steven Rostedt, linux-kernel
  Cc: Divya Indi, Joe Jin, Srinivas Eeda, Aruna Ramakrishna, Manjunath Patil

This is a sample module to demostrate the use of the newly introduced and
exported APIs to access Ftrace instances from within the kernel.

Newly introduced APIs used here -

1. Create a new trace array if it does not exist.
struct trace_array *trace_array_create(const char *name)

2. Destroy/Remove a trace array.
int trace_array_destroy(struct trace_array *tr)

3. Lookup a trace array, given its name.
struct trace_array *trace_array_lookup(const char *name)

4. Enable/Disable trace events:
int trace_array_set_clr_event(struct trace_array *tr, const char *system,
        const char *event, int set);

Exported APIs -
1. trace_printk equivalent for instances.
int trace_array_printk(struct trace_array *tr,
               unsigned long ip, const char *fmt, ...);

2. Helper function.
void trace_printk_init_buffers(void);

3. To decrement the reference counter.
void trace_array_put(struct trace_array *tr)

Signed-off-by: Divya Indi <divya.indi@oracle.com>
Reviewed-by: Manjunath Patil <manjunath.b.patil@oracle.com>
Reviewed-by: Joe Jin <joe.jin@oracle.com>
---
 samples/Kconfig                              |   7 ++
 samples/Makefile                             |   1 +
 samples/ftrace_instance/Makefile             |   6 ++
 samples/ftrace_instance/sample-trace-array.c | 134 +++++++++++++++++++++++++++
 samples/ftrace_instance/sample-trace-array.h |  84 +++++++++++++++++
 5 files changed, 232 insertions(+)
 create mode 100644 samples/ftrace_instance/Makefile
 create mode 100644 samples/ftrace_instance/sample-trace-array.c
 create mode 100644 samples/ftrace_instance/sample-trace-array.h

diff --git a/samples/Kconfig b/samples/Kconfig
index d63cc8a..1c7864b 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -20,6 +20,13 @@ config SAMPLE_TRACE_PRINTK
 	 This builds a module that calls trace_printk() and can be used to
 	 test various trace_printk() calls from a module.
 
+config SAMPLE_TRACE_ARRAY
+        tristate "Build sample module for kernel access to Ftrace instancess"
+	depends on EVENT_TRACING && m
+	help
+	 This builds a module that demonstrates the use of various APIs to
+	 access Ftrace instances from within the kernel.
+
 config SAMPLE_KOBJECT
 	tristate "Build kobject examples"
 	help
diff --git a/samples/Makefile b/samples/Makefile
index debf892..02c444e 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_SAMPLE_RPMSG_CLIENT)	+= rpmsg/
 subdir-$(CONFIG_SAMPLE_SECCOMP)		+= seccomp
 obj-$(CONFIG_SAMPLE_TRACE_EVENTS)	+= trace_events/
 obj-$(CONFIG_SAMPLE_TRACE_PRINTK)	+= trace_printk/
+obj-$(CONFIG_SAMPLE_TRACE_ARRAY)	+= ftrace_instance/
 obj-$(CONFIG_VIDEO_PCI_SKELETON)	+= v4l/
 obj-y					+= vfio-mdev/
 subdir-$(CONFIG_SAMPLE_VFS)		+= vfs
diff --git a/samples/ftrace_instance/Makefile b/samples/ftrace_instance/Makefile
new file mode 100644
index 0000000..3603b13
--- /dev/null
+++ b/samples/ftrace_instance/Makefile
@@ -0,0 +1,6 @@
+# Builds a module that calls various routines to access Ftrace instances.
+# To use(as root):  insmod sample-trace-array.ko
+
+CFLAGS_sample-trace-array.o := -I$(src)
+
+obj-$(CONFIG_SAMPLE_TRACE_ARRAY) += sample-trace-array.o
diff --git a/samples/ftrace_instance/sample-trace-array.c b/samples/ftrace_instance/sample-trace-array.c
new file mode 100644
index 0000000..0595bc7
--- /dev/null
+++ b/samples/ftrace_instance/sample-trace-array.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+#include <linux/kthread.h>
+#include <linux/trace.h>
+#include <linux/trace_events.h>
+#include <linux/timer.h>
+#include <linux/err.h>
+#include <linux/jiffies.h>
+
+/*
+ * Any file that uses trace points, must include the header.
+ * But only one file, must include the header by defining
+ * CREATE_TRACE_POINTS first.  This will make the C code that
+ * creates the handles for the trace points.
+ */
+#define CREATE_TRACE_POINTS
+#include "sample-trace-array.h"
+
+struct trace_array *tr;
+static void mytimer_handler(struct timer_list *unused);
+static struct task_struct *simple_tsk;
+
+/*
+ * mytimer: Timer setup to disable tracing for event "sample_event". This
+ * timer is only for the purposes of the sample module to demonstrate access of
+ * Ftrace instances from within kernel.
+ */
+static DEFINE_TIMER(mytimer, mytimer_handler);
+
+static void mytimer_handler(struct timer_list *unused)
+{
+	/*
+	 * Disable tracing for event "sample_event".
+	 */
+	trace_array_set_clr_event(tr, "sample-subsystem", "sample_event", 0);
+}
+
+static void simple_thread_func(int count)
+{
+	set_current_state(TASK_INTERRUPTIBLE);
+	schedule_timeout(HZ);
+
+	/*
+	 * Printing count value using trace_array_printk() - trace_printk()
+	 * equivalent for the instance buffers.
+	 */
+	trace_array_printk(tr, _THIS_IP_, "trace_array_printk: count=%d\n",
+			count);
+	/*
+	 * Tracepoint for event "sample_event". This will print the
+	 * current value of count and current jiffies.
+	 */
+	trace_sample_event(count, jiffies);
+}
+
+static int simple_thread(void *arg)
+{
+	int count = 0;
+	unsigned long delay = msecs_to_jiffies(5000);
+
+	/*
+	 * Enable tracing for "sample_event".
+	 */
+	trace_array_set_clr_event(tr, "sample-subsystem", "sample_event", 1);
+
+	/*
+	 * Adding timer - mytimer. This timer will disable tracing after
+	 * delay seconds.
+	 *
+	 */
+	add_timer(&mytimer);
+	mod_timer(&mytimer, jiffies+delay);
+
+	while (!kthread_should_stop())
+		simple_thread_func(count++);
+
+	del_timer(&mytimer);
+
+	/*
+	 * trace_array_put() decrements the reference counter associated with
+	 * the trace array - "tr". We are done using the trace array, hence
+	 * decrement the reference counter so that it can be destroyed using
+	 * trace_array_destroy().
+	 */
+	trace_array_put(tr);
+
+	return 0;
+}
+
+static int __init sample_trace_array_init(void)
+{
+	/*
+	 * If a trace array with name "sample-instance" already exists, get a
+	 * handle to it via trace_array_lookup. Else, create one using
+	 * trace_array_create().
+	 *
+	 * NOTE: Both these functions increment the reference counter
+	 * associated with the trace array - "tr".
+	 */
+	tr = trace_array_lookup("sample-instance");
+	if (!tr)
+		tr = trace_array_create("sample-instance");
+
+	if (IS_ERR(tr))
+		return PTR_ERR(tr);
+
+	/*
+	 * If context specific per-cpu buffers havent already been allocated.
+	 */
+	trace_printk_init_buffers();
+
+	simple_tsk = kthread_run(simple_thread, NULL, "sample-instance");
+	if (IS_ERR(simple_tsk))
+		return -1;
+	return 0;
+}
+
+static void __exit sample_trace_array_exit(void)
+{
+	kthread_stop(simple_tsk);
+
+	/*
+	 * We are unloading our module and no longer require the trace array.
+	 * Remove/destroy "tr" using trace_array_destroy()
+	 */
+	trace_array_destroy(tr);
+}
+
+module_init(sample_trace_array_init);
+module_exit(sample_trace_array_exit);
+
+MODULE_AUTHOR("Divya Indi");
+MODULE_DESCRIPTION("Sample module for kernel access to Ftrace instances");
+MODULE_LICENSE("GPL");
diff --git a/samples/ftrace_instance/sample-trace-array.h b/samples/ftrace_instance/sample-trace-array.h
new file mode 100644
index 0000000..547ad56
--- /dev/null
+++ b/samples/ftrace_instance/sample-trace-array.h
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/*
+ * If TRACE_SYSTEM is defined, that will be the directory created
+ * in the ftrace directory under /sys/kernel/tracing/events/<system>
+ *
+ * The define_trace.h below will also look for a file name of
+ * TRACE_SYSTEM.h where TRACE_SYSTEM is what is defined here.
+ * In this case, it would look for sample-trace.h
+ *
+ * If the header name will be different than the system name
+ * (as in this case), then you can override the header name that
+ * define_trace.h will look up by defining TRACE_INCLUDE_FILE
+ *
+ * This file is called sample-trace-array.h but we want the system
+ * to be called "sample-subsystem". Therefore we must define the name of this
+ * file:
+ *
+ * #define TRACE_INCLUDE_FILE sample-trace-array
+ *
+ * As we do in the bottom of this file.
+ *
+ * Notice that TRACE_SYSTEM should be defined outside of #if
+ * protection, just like TRACE_INCLUDE_FILE.
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM sample-subsystem
+
+/*
+ * TRACE_SYSTEM is expected to be a C valid variable (alpha-numeric
+ * and underscore), although it may start with numbers. If for some
+ * reason it is not, you need to add the following lines:
+ */
+#undef TRACE_SYSTEM_VAR
+#define TRACE_SYSTEM_VAR sample_subsystem
+
+/*
+ * But the above is only needed if TRACE_SYSTEM is not alpha-numeric
+ * and underscored. By default, TRACE_SYSTEM_VAR will be equal to
+ * TRACE_SYSTEM. As TRACE_SYSTEM_VAR must be alpha-numeric, if
+ * TRACE_SYSTEM is not, then TRACE_SYSTEM_VAR must be defined with
+ * only alpha-numeric and underscores.
+ *
+ * The TRACE_SYSTEM_VAR is only used internally and not visible to
+ * user space.
+ */
+
+/*
+ * Notice that this file is not protected like a normal header.
+ * We also must allow for rereading of this file. The
+ *
+ *  || defined(TRACE_HEADER_MULTI_READ)
+ *
+ * serves this purpose.
+ */
+#if !defined(_SAMPLE_TRACE_ARRAY_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _SAMPLE_TRACE_ARRAY_H
+
+#include <linux/tracepoint.h>
+TRACE_EVENT(sample_event,
+
+	TP_PROTO(int count, unsigned long time),
+
+	TP_ARGS(count, time),
+
+	TP_STRUCT__entry(
+		__field(	int,	count			)
+		__field(	unsigned long,	time		)
+	),
+
+	TP_fast_assign(
+		__entry->count = count;
+		__entry->time = time;
+	),
+
+	TP_printk("count value=%d at jiffies=%lu", __entry->count,
+		__entry->time)
+	);
+#endif
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#define TRACE_INCLUDE_FILE sample-trace-array
+#include <trace/define_trace.h>
-- 
1.8.3.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] tracing: Sample module to demonstrate kernel access to Ftrace instances.
  2019-09-20 23:59 ` [PATCH] tracing: Sample module to demonstrate kernel " Divya Indi
@ 2019-10-15 17:05   ` Steven Rostedt
  2019-10-15 19:53     ` Divya Indi
  0 siblings, 1 reply; 4+ messages in thread
From: Steven Rostedt @ 2019-10-15 17:05 UTC (permalink / raw)
  To: Divya Indi
  Cc: linux-kernel, Joe Jin, Srinivas Eeda, Aruna Ramakrishna, Manjunath Patil

On Fri, 20 Sep 2019 16:59:26 -0700
Divya Indi <divya.indi@oracle.com> wrote:

> This is a sample module to demostrate the use of the newly introduced and
> exported APIs to access Ftrace instances from within the kernel.
> 
> Newly introduced APIs used here -
> 
> 1. Create a new trace array if it does not exist.
> struct trace_array *trace_array_create(const char *name)
> 
> 2. Destroy/Remove a trace array.
> int trace_array_destroy(struct trace_array *tr)
> 
> 3. Lookup a trace array, given its name.
> struct trace_array *trace_array_lookup(const char *name)
> 
> 4. Enable/Disable trace events:
> int trace_array_set_clr_event(struct trace_array *tr, const char *system,
>         const char *event, int set);
> 
> Exported APIs -
> 1. trace_printk equivalent for instances.
> int trace_array_printk(struct trace_array *tr,
>                unsigned long ip, const char *fmt, ...);
> 
> 2. Helper function.
> void trace_printk_init_buffers(void);
> 
> 3. To decrement the reference counter.
> void trace_array_put(struct trace_array *tr)
> 
> Signed-off-by: Divya Indi <divya.indi@oracle.com>
> Reviewed-by: Manjunath Patil <manjunath.b.patil@oracle.com>
> Reviewed-by: Joe Jin <joe.jin@oracle.com>
> ---
>  samples/Kconfig                              |   7 ++
>  samples/Makefile                             |   1 +
>  samples/ftrace_instance/Makefile             |   6 ++
>  samples/ftrace_instance/sample-trace-array.c | 134 +++++++++++++++++++++++++++
>  samples/ftrace_instance/sample-trace-array.h |  84 +++++++++++++++++
>  5 files changed, 232 insertions(+)
>  create mode 100644 samples/ftrace_instance/Makefile
>  create mode 100644 samples/ftrace_instance/sample-trace-array.c
>  create mode 100644 samples/ftrace_instance/sample-trace-array.h
>

I applied this patch but get this:

/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘mytimer_handler’:
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:35:2: error: implicit declaration of function ‘trace_array_set_clr_event’; did you mean ‘trace_set_clr_event’? [-Werror=implicit-function-declaration]
  trace_array_set_clr_event(tr, "sample-subsystem", "sample_event", 0);
  ^~~~~~~~~~~~~~~~~~~~~~~~~
  trace_set_clr_event
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘simple_thread_func’:
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:47:2: error: implicit declaration of function ‘trace_array_printk’; did you mean ‘trace_seq_printf’? [-Werror=implicit-function-declaration]
  trace_array_printk(tr, _THIS_IP_, "trace_array_printk: count=%d\n",
  ^~~~~~~~~~~~~~~~~~
  trace_seq_printf
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘simple_thread’:
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:85:2: error: implicit declaration of function ‘trace_array_put’; did you mean ‘trace_seq_putc’? [-Werror=implicit-function-declaration]
  trace_array_put(tr);
  ^~~~~~~~~~~~~~~
  trace_seq_putc
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘sample_trace_array_init’:
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:100:7: error: implicit declaration of function ‘trace_array_lookup’; did you mean ‘radix_tree_lookup’? [-Werror=implicit-function-declaration]
  tr = trace_array_lookup("sample-instance");
       ^~~~~~~~~~~~~~~~~~
       radix_tree_lookup
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:100:5: warning: assignment to ‘struct trace_array *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
  tr = trace_array_lookup("sample-instance");
     ^
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:102:8: error: implicit declaration of function ‘trace_array_create’; did you mean ‘ftrace_force_update’? [-Werror=implicit-function-declaration]
   tr = trace_array_create("sample-instance");
        ^~~~~~~~~~~~~~~~~~
        ftrace_force_update
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:102:6: warning: assignment to ‘struct trace_array *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
   tr = trace_array_create("sample-instance");
      ^
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:110:2: error: implicit declaration of function ‘trace_printk_init_buffers’; did you mean ‘trace_event_get_offsets’? [-Werror=implicit-function-declaration]
  trace_printk_init_buffers();
  ^~~~~~~~~~~~~~~~~~~~~~~~~
  trace_event_get_offsets
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘sample_trace_array_exit’:
/work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:126:2: error: implicit declaration of function ‘trace_array_destroy’; did you mean ‘assoc_array_destroy’? [-Werror=implicit-function-declaration]
  trace_array_destroy(tr);
  ^~~~~~~~~~~~~~~~~~~
  assoc_array_destroy
cc1: some warnings being treated as errors
make[3]: *** [/work/git/linux-trace.git/scripts/Makefile.build:266: samples/ftrace_instance/sample-trace-array.o] Error 1
make[2]: *** [/work/git/linux-trace.git/scripts/Makefile.build:509: samples/ftrace_instance] Error 2
make[1]: *** [/work/git/linux-trace.git/Makefile:1650: samples] Error 2
make[1]: *** Waiting for unfinished jobs....


-- Steve

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] tracing: Sample module to demonstrate kernel access to Ftrace instances.
  2019-10-15 17:05   ` Steven Rostedt
@ 2019-10-15 19:53     ` Divya Indi
  0 siblings, 0 replies; 4+ messages in thread
From: Divya Indi @ 2019-10-15 19:53 UTC (permalink / raw)
  To: Steven Rostedt
  Cc: linux-kernel, Joe Jin, Srinivas Eeda, Aruna Ramakrishna, Manjunath Patil

[Apologies for multiple resends, formatting issue]


Hi Steven,


Thanks for taking a look.

This sample module is dependent on -

- commit: f45d122 tracing: Kernel access to Ftrace instances
- Patches pending review: https://lore.kernel.org/lkml/1565805327-579-1-git-send-email-divya.indi@oracle.com/

I mentioned it in the cover page, but will add to this patch as well to avoid confusion.

So, I think the messages you are seeing is due to the absence of

Patches pending review: https://lore.kernel.org/lkml/1565805327-579-1-git-send-email-divya.indi@oracle.com/


Let me know if you prefer to have the sample module and this patch-set (pending review) as part of one patch set.

For reference, adding the cover page details here -

------------------------------------------------------------------------------------------------------------------
This patch is for a sample module to demonstrate the use of APIs that
were introduced/exported in order to access Ftrace instances from within the kernel.

Please Note: This module is dependent on -
- commit: f45d122 tracing: Kernel access to Ftrace instances
- Patches pending review: https://lore.kernel.org/lkml/1565805327-579-1-git-send-email-divya.indi@oracle.com/

The sample module creates/lookup a trace array called sample-instance on module load time.
We then start a kernel thread(simple-thread) to -
1) Enable tracing for event "sample_event" to buffer associated with the trace array - "sample-instance".
2) Start a timer that will disable tracing to this buffer after 5 sec. (Tracing disabled after 5 sec ie at count=4)
3) Write to the buffer using trace_array_printk()
4) Stop the kernel thread and destroy the buffer during module unload.

A sample output for the same -

# tracer: nop
#
# entries-in-buffer/entries-written: 16/16   #P:4
#
#                              _-----=> irqs-off
#                             / _----=> need-resched
#                            | / _---=> hardirq/softirq
#                            || / _--=> preempt-depth
#                            ||| /     delay
#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
#              | |       |   ||||       |         |
  sample-instance-26797 [003] .... 955180.489833: simple_thread: trace_array_printk: count=0
  sample-instance-26797 [003] .... 955180.489836: sample_event: count value=0 at jiffies=5249940864
  sample-instance-26797 [003] .... 955181.513722: simple_thread: trace_array_printk: count=1
  sample-instance-26797 [003] .... 955181.513724: sample_event: count value=1 at jiffies=5249941888
  sample-instance-26797 [003] .... 955182.537629: simple_thread: trace_array_printk: count=2
  sample-instance-26797 [003] .... 955182.537631: sample_event: count value=2 at jiffies=5249942912
  sample-instance-26797 [003] .... 955183.561516: simple_thread: trace_array_printk: count=3
  sample-instance-26797 [003] .... 955183.561518: sample_event: count value=3 at jiffies=5249943936
  sample-instance-26797 [003] .... 955184.585423: simple_thread: trace_array_printk: count=4
  sample-instance-26797 [003] .... 955184.585427: sample_event: count value=4 at jiffies=5249944960
  sample-instance-26797 [003] .... 955185.609344: simple_thread: trace_array_printk: count=5
  sample-instance-26797 [003] .... 955186.633241: simple_thread: trace_array_printk: count=6
  sample-instance-26797 [003] .... 955187.657157: simple_thread: trace_array_printk: count=7
  sample-instance-26797 [003] .... 955188.681039: simple_thread: trace_array_printk: count=8
  sample-instance-26797 [003] .... 955189.704937: simple_thread: trace_array_printk: count=9
  sample-instance-26797 [003] .... 955190.728840: simple_thread: trace_array_printk: count=10

--------------------------------------------------------------------------------------------------------------------


Thanks,
Divya

On 10/15/19 10:05 AM, Steven Rostedt wrote:
> On Fri, 20 Sep 2019 16:59:26 -0700
> Divya Indi <divya.indi@oracle.com> wrote:
>
>> This is a sample module to demostrate the use of the newly introduced and
>> exported APIs to access Ftrace instances from within the kernel.
>>
>> Newly introduced APIs used here -
>>
>> 1. Create a new trace array if it does not exist.
>> struct trace_array *trace_array_create(const char *name)
>>
>> 2. Destroy/Remove a trace array.
>> int trace_array_destroy(struct trace_array *tr)
>>
>> 3. Lookup a trace array, given its name.
>> struct trace_array *trace_array_lookup(const char *name)
>>
>> 4. Enable/Disable trace events:
>> int trace_array_set_clr_event(struct trace_array *tr, const char *system,
>>          const char *event, int set);
>>
>> Exported APIs -
>> 1. trace_printk equivalent for instances.
>> int trace_array_printk(struct trace_array *tr,
>>                 unsigned long ip, const char *fmt, ...);
>>
>> 2. Helper function.
>> void trace_printk_init_buffers(void);
>>
>> 3. To decrement the reference counter.
>> void trace_array_put(struct trace_array *tr)
>>
>> Signed-off-by: Divya Indi <divya.indi@oracle.com>
>> Reviewed-by: Manjunath Patil <manjunath.b.patil@oracle.com>
>> Reviewed-by: Joe Jin <joe.jin@oracle.com>
>> ---
>>   samples/Kconfig                              |   7 ++
>>   samples/Makefile                             |   1 +
>>   samples/ftrace_instance/Makefile             |   6 ++
>>   samples/ftrace_instance/sample-trace-array.c | 134 +++++++++++++++++++++++++++
>>   samples/ftrace_instance/sample-trace-array.h |  84 +++++++++++++++++
>>   5 files changed, 232 insertions(+)
>>   create mode 100644 samples/ftrace_instance/Makefile
>>   create mode 100644 samples/ftrace_instance/sample-trace-array.c
>>   create mode 100644 samples/ftrace_instance/sample-trace-array.h
>>
> I applied this patch but get this:
>
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘mytimer_handler’:
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:35:2: error: implicit declaration of function ‘trace_array_set_clr_event’; did you mean ‘trace_set_clr_event’? [-Werror=implicit-function-declaration]
>    trace_array_set_clr_event(tr, "sample-subsystem", "sample_event", 0);
>    ^~~~~~~~~~~~~~~~~~~~~~~~~
>    trace_set_clr_event
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘simple_thread_func’:
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:47:2: error: implicit declaration of function ‘trace_array_printk’; did you mean ‘trace_seq_printf’? [-Werror=implicit-function-declaration]
>    trace_array_printk(tr, _THIS_IP_, "trace_array_printk: count=%d\n",
>    ^~~~~~~~~~~~~~~~~~
>    trace_seq_printf
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘simple_thread’:
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:85:2: error: implicit declaration of function ‘trace_array_put’; did you mean ‘trace_seq_putc’? [-Werror=implicit-function-declaration]
>    trace_array_put(tr);
>    ^~~~~~~~~~~~~~~
>    trace_seq_putc
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘sample_trace_array_init’:
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:100:7: error: implicit declaration of function ‘trace_array_lookup’; did you mean ‘radix_tree_lookup’? [-Werror=implicit-function-declaration]
>    tr = trace_array_lookup("sample-instance");
>         ^~~~~~~~~~~~~~~~~~
>         radix_tree_lookup
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:100:5: warning: assignment to ‘struct trace_array *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
>    tr = trace_array_lookup("sample-instance");
>       ^
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:102:8: error: implicit declaration of function ‘trace_array_create’; did you mean ‘ftrace_force_update’? [-Werror=implicit-function-declaration]
>     tr = trace_array_create("sample-instance");
>          ^~~~~~~~~~~~~~~~~~
>          ftrace_force_update
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:102:6: warning: assignment to ‘struct trace_array *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
>     tr = trace_array_create("sample-instance");
>        ^
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:110:2: error: implicit declaration of function ‘trace_printk_init_buffers’; did you mean ‘trace_event_get_offsets’? [-Werror=implicit-function-declaration]
>    trace_printk_init_buffers();
>    ^~~~~~~~~~~~~~~~~~~~~~~~~
>    trace_event_get_offsets
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c: In function ‘sample_trace_array_exit’:
> /work/git/linux-trace.git/samples/ftrace_instance/sample-trace-array.c:126:2: error: implicit declaration of function ‘trace_array_destroy’; did you mean ‘assoc_array_destroy’? [-Werror=implicit-function-declaration]
>    trace_array_destroy(tr);
>    ^~~~~~~~~~~~~~~~~~~
>    assoc_array_destroy
> cc1: some warnings being treated as errors
> make[3]: *** [/work/git/linux-trace.git/scripts/Makefile.build:266: samples/ftrace_instance/sample-trace-array.o] Error 1
> make[2]: *** [/work/git/linux-trace.git/scripts/Makefile.build:509: samples/ftrace_instance] Error 2
> make[1]: *** [/work/git/linux-trace.git/Makefile:1650: samples] Error 2
> make[1]: *** Waiting for unfinished jobs....
>
>
> -- Steve

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-10-15 19:54 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-20 23:59 [RFC]Sample module for Kernel access to Ftrace instances Divya Indi
2019-09-20 23:59 ` [PATCH] tracing: Sample module to demonstrate kernel " Divya Indi
2019-10-15 17:05   ` Steven Rostedt
2019-10-15 19:53     ` Divya Indi

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