* [PATCH for tip][bugfix] ftrace: fix deadlock when setting set_ftrace_pid
@ 2009-03-06 6:29 KOSAKI Motohiro
2009-03-06 6:57 ` Lai Jiangshan
2009-03-06 11:09 ` [tip:tracing/ftrace] tracing: " KOSAKI Motohiro
0 siblings, 2 replies; 4+ messages in thread
From: KOSAKI Motohiro @ 2009-03-06 6:29 UTC (permalink / raw)
To: LKML, Steven Rostedt, Ingo Molnar; +Cc: kosaki.motohiro
Impact: fix deadlock bug
reproduce way:
# cd /sys/kernel/debug/tracing
# echo $$ > set_ftrace_pid
then, console become hangup.
detail:
when writing set_ftracepid, kernel callstack is following
ftrace_pid_write()
mutex_lock(&ftrace_lock);
ftrace_update_pid_func()
mutex_lock(&ftrace_lock);
mutex_unlock(&ftrace_lock);
mutex_unlock(&ftrace_lock);
then, system alaways deadlock when ftrace_pid_write() is called.
In past days, ftrace_pid_write() use ftrace_start_lock, but
commit e6ea44e9b4c12325337cd1c06103cd515a1c02b2 consolidate
ftrace_start_lock to ftrace_lock.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 5a3a06b..0d3b393 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -218,10 +218,8 @@ static void ftrace_update_pid_func(void)
{
ftrace_func_t func;
- mutex_lock(&ftrace_lock);
-
if (ftrace_trace_function == ftrace_stub)
- goto out;
+ return;
func = ftrace_trace_function;
@@ -238,9 +236,6 @@ static void ftrace_update_pid_func(void)
#else
__ftrace_trace_function = func;
#endif
-
- out:
- mutex_unlock(&ftrace_lock);
}
/* set when tracing only a pid */
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH for tip][bugfix] ftrace: fix deadlock when setting set_ftrace_pid
2009-03-06 6:29 [PATCH for tip][bugfix] ftrace: fix deadlock when setting set_ftrace_pid KOSAKI Motohiro
@ 2009-03-06 6:57 ` Lai Jiangshan
2009-03-06 11:08 ` Ingo Molnar
2009-03-06 11:09 ` [tip:tracing/ftrace] tracing: " KOSAKI Motohiro
1 sibling, 1 reply; 4+ messages in thread
From: Lai Jiangshan @ 2009-03-06 6:57 UTC (permalink / raw)
To: KOSAKI Motohiro; +Cc: LKML, Steven Rostedt, Ingo Molnar
KOSAKI Motohiro wrote:
> Impact: fix deadlock bug
>
> reproduce way:
> # cd /sys/kernel/debug/tracing
> # echo $$ > set_ftrace_pid
>
> then, console become hangup.
>
> detail:
> when writing set_ftracepid, kernel callstack is following
>
> ftrace_pid_write()
> mutex_lock(&ftrace_lock);
> ftrace_update_pid_func()
> mutex_lock(&ftrace_lock);
> mutex_unlock(&ftrace_lock);
> mutex_unlock(&ftrace_lock);
>
> then, system alaways deadlock when ftrace_pid_write() is called.
>
> In past days, ftrace_pid_write() use ftrace_start_lock, but
> commit e6ea44e9b4c12325337cd1c06103cd515a1c02b2 consolidate
> ftrace_start_lock to ftrace_lock.
>
>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> ---
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 5a3a06b..0d3b393 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -218,10 +218,8 @@ static void ftrace_update_pid_func(void)
> {
> ftrace_func_t func;
>
> - mutex_lock(&ftrace_lock);
> -
> if (ftrace_trace_function == ftrace_stub)
> - goto out;
> + return;
>
> func = ftrace_trace_function;
>
> @@ -238,9 +236,6 @@ static void ftrace_update_pid_func(void)
> #else
> __ftrace_trace_function = func;
> #endif
> -
> - out:
> - mutex_unlock(&ftrace_lock);
> }
>
> /* set when tracing only a pid */
>
>
Reviewed-By: Lai Jiangshan <laijs@cn.fujitsu.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH for tip][bugfix] ftrace: fix deadlock when setting set_ftrace_pid
2009-03-06 6:57 ` Lai Jiangshan
@ 2009-03-06 11:08 ` Ingo Molnar
0 siblings, 0 replies; 4+ messages in thread
From: Ingo Molnar @ 2009-03-06 11:08 UTC (permalink / raw)
To: Lai Jiangshan; +Cc: KOSAKI Motohiro, LKML, Steven Rostedt
* Lai Jiangshan <laijs@cn.fujitsu.com> wrote:
> KOSAKI Motohiro wrote:
> > Impact: fix deadlock bug
> >
> > reproduce way:
> > # cd /sys/kernel/debug/tracing
> > # echo $$ > set_ftrace_pid
> >
> > then, console become hangup.
> >
> > detail:
> > when writing set_ftracepid, kernel callstack is following
> >
> > ftrace_pid_write()
> > mutex_lock(&ftrace_lock);
> > ftrace_update_pid_func()
> > mutex_lock(&ftrace_lock);
> > mutex_unlock(&ftrace_lock);
> > mutex_unlock(&ftrace_lock);
> >
> > then, system alaways deadlock when ftrace_pid_write() is called.
> >
> > In past days, ftrace_pid_write() use ftrace_start_lock, but
> > commit e6ea44e9b4c12325337cd1c06103cd515a1c02b2 consolidate
> > ftrace_start_lock to ftrace_lock.
> >
> >
> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> > ---
> > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> > index 5a3a06b..0d3b393 100644
> > --- a/kernel/trace/ftrace.c
> > +++ b/kernel/trace/ftrace.c
> > @@ -218,10 +218,8 @@ static void ftrace_update_pid_func(void)
> > {
> > ftrace_func_t func;
> >
> > - mutex_lock(&ftrace_lock);
> > -
> > if (ftrace_trace_function == ftrace_stub)
> > - goto out;
> > + return;
> >
> > func = ftrace_trace_function;
> >
> > @@ -238,9 +236,6 @@ static void ftrace_update_pid_func(void)
> > #else
> > __ftrace_trace_function = func;
> > #endif
> > -
> > - out:
> > - mutex_unlock(&ftrace_lock);
> > }
> >
> > /* set when tracing only a pid */
> >
> >
>
> Reviewed-By: Lai Jiangshan <laijs@cn.fujitsu.com>
Applied, thanks!
Ingo
^ permalink raw reply [flat|nested] 4+ messages in thread
* [tip:tracing/ftrace] tracing: fix deadlock when setting set_ftrace_pid
2009-03-06 6:29 [PATCH for tip][bugfix] ftrace: fix deadlock when setting set_ftrace_pid KOSAKI Motohiro
2009-03-06 6:57 ` Lai Jiangshan
@ 2009-03-06 11:09 ` KOSAKI Motohiro
1 sibling, 0 replies; 4+ messages in thread
From: KOSAKI Motohiro @ 2009-03-06 11:09 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, hpa, mingo, srostedt, tglx, laijs, kosaki.motohiro,
mingo
Commit-ID: 10dd3ebe213c31bff14b4dae3c5d32a76b1fad7c
Gitweb: http://git.kernel.org/tip/10dd3ebe213c31bff14b4dae3c5d32a76b1fad7c
Author: "KOSAKI Motohiro" <kosaki.motohiro@jp.fujitsu.com>
AuthorDate: Fri, 6 Mar 2009 15:29:04 +0900
Commit: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 6 Mar 2009 12:07:38 +0100
tracing: fix deadlock when setting set_ftrace_pid
Impact: fix deadlock while using set_ftrace_pid
Reproducer:
# cd /sys/kernel/debug/tracing
# echo $$ > set_ftrace_pid
then, console becomes hung.
Details:
when writing set_ftracepid, kernel callstack is following
ftrace_pid_write()
mutex_lock(&ftrace_lock);
ftrace_update_pid_func()
mutex_lock(&ftrace_lock);
mutex_unlock(&ftrace_lock);
mutex_unlock(&ftrace_lock);
then, system always deadlocks when ftrace_pid_write() is called.
In past days, ftrace_pid_write() used ftrace_start_lock, but
commit e6ea44e9b4c12325337cd1c06103cd515a1c02b2 consolidated
ftrace_start_lock to ftrace_lock.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <20090306151155.0778.A69D9226@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/trace/ftrace.c | 7 +------
1 files changed, 1 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index d7a06a0..d33d306 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -218,10 +218,8 @@ static void ftrace_update_pid_func(void)
{
ftrace_func_t func;
- mutex_lock(&ftrace_lock);
-
if (ftrace_trace_function == ftrace_stub)
- goto out;
+ return;
func = ftrace_trace_function;
@@ -238,9 +236,6 @@ static void ftrace_update_pid_func(void)
#else
__ftrace_trace_function = func;
#endif
-
- out:
- mutex_unlock(&ftrace_lock);
}
/* set when tracing only a pid */
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2009-03-06 11:10 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2009-03-06 6:29 [PATCH for tip][bugfix] ftrace: fix deadlock when setting set_ftrace_pid KOSAKI Motohiro
2009-03-06 6:57 ` Lai Jiangshan
2009-03-06 11:08 ` Ingo Molnar
2009-03-06 11:09 ` [tip:tracing/ftrace] tracing: " KOSAKI Motohiro
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