[PATCH 0/3] [GIT PULL] tracing: updates

[PATCH 0/3] [GIT PULL] tracing: updates

[Steven Rostedt]

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Ingo,

I based this branch off of my tip/perf/core that I sent a pull request
for earlier.

Please pull the latest tip/perf/core-2 tree, which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
tip/perf/core-2

Head SHA1: 87abb3b15c62033409f5bf2ffb5620c94f91cf2c


Jiri Olsa (1):
      tracing/filter: Add missing initialization

Steven Rostedt (1):
      tracing: Fix wakeup_rt self test on virtual machines

Wang Tianhong (1):
      tracing/trivial: Fix some typos in kernel/trace

----
 kernel/trace/ring_buffer.c         |    4 ++--
 kernel/trace/trace.c               |    6 +++---
 kernel/trace/trace_events_filter.c |    2 +-
 kernel/trace/trace_selftest.c      |   27 +++++++++++++--------------
 4 files changed, 19 insertions(+), 20 deletions(-)

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[PATCH 1/3] tracing: Fix wakeup_rt self test on virtual machines

[Steven Rostedt]

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From: Steven Rostedt <srostedt@redhat.com>

The warkeup_rt self test used msleep() calls to wait for real time
tasks to wake up and run. On bare-metal hardware, this was enough as
the scheduler should let the RT task run way before the non-RT task
wakes up from the msleep(). If it did not, then that would mean the
scheduler was broken.

But when dealing with virtual machines, this is a different story.
If the RT task wakes up on a VCPU, it's up to the host to decide when
that task gets to schedule, which can be far behind the time that the
non-RT task wakes up. In this case, the test would fail incorrectly.

As we are not testing the scheduler, but instead the wake up tracing,
we can use completions to wait and not depend on scheduler timings
to see if events happen on time.

Link: http://lkml.kernel.org/r/1343663105.3847.7.camel@fedora

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_selftest.c |   27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 1003a4d..2c00a69 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -1041,6 +1041,8 @@ static int trace_wakeup_test_thread(void *data)
 	set_current_state(TASK_INTERRUPTIBLE);
 	schedule();
 
+	complete(x);
+
 	/* we are awake, now wait to disappear */
 	while (!kthread_should_stop()) {
 		/*
@@ -1084,24 +1086,21 @@ trace_selftest_startup_wakeup(struct tracer *trace, struct trace_array *tr)
 	/* reset the max latency */
 	tracing_max_latency = 0;
 
-	/* sleep to let the RT thread sleep too */
-	msleep(100);
+	while (p->on_rq) {
+		/*
+		 * Sleep to make sure the RT thread is asleep too.
+		 * On virtual machines we can't rely on timings,
+		 * but we want to make sure this test still works.
+		 */
+		msleep(100);
+	}
 
-	/*
-	 * Yes this is slightly racy. It is possible that for some
-	 * strange reason that the RT thread we created, did not
-	 * call schedule for 100ms after doing the completion,
-	 * and we do a wakeup on a task that already is awake.
-	 * But that is extremely unlikely, and the worst thing that
-	 * happens in such a case, is that we disable tracing.
-	 * Honestly, if this race does happen something is horrible
-	 * wrong with the system.
-	 */
+	init_completion(&isrt);
 
 	wake_up_process(p);
 
-	/* give a little time to let the thread wake up */
-	msleep(100);
+	/* Wait for the task to wake up */
+	wait_for_completion(&isrt);
 
 	/* stop the tracing. */
 	tracing_stop();
-- 
1.7.10.4



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[PATCH 2/3] tracing/filter: Add missing initialization

[Steven Rostedt]

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From: Jiri Olsa <jolsa@redhat.com>

Add missing initialization for ret variable. Its initialization
is based on the re_cnt variable, which is being set deep down
in the ftrace_function_filter_re function.

I'm not sure compilers would be smart enough to see this in near
future, so killing the warning this way.

Link: http://lkml.kernel.org/r/1340120894-9465-2-git-send-email-jolsa@redhat.com

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace_events_filter.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 431dba8..c154797 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -2002,7 +2002,7 @@ static int ftrace_function_set_regexp(struct ftrace_ops *ops, int filter,
 static int __ftrace_function_set_filter(int filter, char *buf, int len,
 					struct function_filter_data *data)
 {
-	int i, re_cnt, ret;
+	int i, re_cnt, ret = -EINVAL;
 	int *reset;
 	char **re;
 
-- 
1.7.10.4



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[PATCH 3/3] tracing/trivial: Fix some typos in kernel/trace

[Steven Rostedt]

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From: Wang Tianhong <wangthbj@linux.vnet.ibm.com>

Fix some typos in kernel/trace.

Link: http://lkml.kernel.org/r/1343887320.2228.9.camel@louis-ThinkPad-T410

Signed-off-by: Wang Tianhong <wangthbj@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/ring_buffer.c |    4 ++--
 kernel/trace/trace.c       |    6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 49491fa..b32ed0e 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2816,7 +2816,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_enable);
  * to the buffer after this will fail and return NULL.
  *
  * This is different than ring_buffer_record_disable() as
- * it works like an on/off switch, where as the disable() verison
+ * it works like an on/off switch, where as the disable() version
  * must be paired with a enable().
  */
 void ring_buffer_record_off(struct ring_buffer *buffer)
@@ -2839,7 +2839,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_off);
  * ring_buffer_record_off().
  *
  * This is different than ring_buffer_record_enable() as
- * it works like an on/off switch, where as the enable() verison
+ * it works like an on/off switch, where as the enable() version
  * must be paired with a disable().
  */
 void ring_buffer_record_on(struct ring_buffer *buffer)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a120f98..d1a8d07 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -426,15 +426,15 @@ __setup("trace_buf_size=", set_buf_size);
 
 static int __init set_tracing_thresh(char *str)
 {
-	unsigned long threshhold;
+	unsigned long threshold;
 	int ret;
 
 	if (!str)
 		return 0;
-	ret = strict_strtoul(str, 0, &threshhold);
+	ret = strict_strtoul(str, 0, &threshold);
 	if (ret < 0)
 		return 0;
-	tracing_thresh = threshhold * 1000;
+	tracing_thresh = threshold * 1000;
 	return 1;
 }
 __setup("tracing_thresh=", set_tracing_thresh);
-- 
1.7.10.4



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