[PATCH][GIT PULL] tracing: add trace_stack interface

[PATCH][GIT PULL] tracing: add trace_stack interface

[Steven Rostedt]

Ingo,

Please pull the latest tip/tracing/ftrace tree, which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
tip/tracing/ftrace


Steven Rostedt (1):
      tracing: add trace_stack interface

----
 include/linux/kernel.h |    2 ++
 kernel/trace/trace.c   |   15 +++++++++++++++
 2 files changed, 17 insertions(+), 0 deletions(-)
---------------------------
commit b85d1029ba534376d203c3ac83a2e5a4d6876cb6
Author: Steven Rostedt <srostedt@redhat.com>
Date:   Tue May 19 18:54:16 2009 -0400

    tracing: add trace_stack interface
    
    This patch adds the global function
    
      void trace_stack(void)
    
    This allows a developer to find where a function is called. For example,
    if you want to know who calls __netif_reschedule, you can add
    
     static inline void __netif_reschedule(struct Qdisc *q)
     {
     	struct softnet_data *sd;
     	unsigned long flags;
    
    +	trace_stack();
     	local_irq_save(flags);
     	sd = &__get_cpu_var(softnet_data);
     	q->next_sched = sd->output_queue;
    
    And see the following in the trace output:
    
     <= __ftrace_trace_stack
     <= trace_stack
     <= __netif_schedule
     <= dev_watchdog
     <= run_timer_softirq
     <= __do_softirq
     <= call_softirq
     <= do_softirq
     <= irq_exit
    
    Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 883cd44..347a0f1 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -511,6 +511,7 @@ extern int
 __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 
 extern void ftrace_dump(void);
+extern void trace_stack(void);
 #else
 static inline void
 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
@@ -531,6 +532,7 @@ ftrace_vprintk(const char *fmt, va_list ap)
 	return 0;
 }
 static inline void ftrace_dump(void) { }
+static inline void trace_stack(void) { }
 #endif /* CONFIG_TRACING */
 
 /*
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dd40d23..33ab502 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1046,6 +1046,21 @@ void __trace_stack(struct trace_array *tr,
 	__ftrace_trace_stack(tr, flags, skip, pc);
 }
 
+/**
+ * trace_stack - dump the stack into the trace buffer
+ *
+ * Use this to record the stack trace into the ring buffer. If you
+ * want to know a caller of a function, place a call to trace_stack
+ * and the ftrace trace file will display who the callers were.
+ */
+void trace_stack(void)
+{
+	unsigned long flags;
+
+	local_save_flags(flags);
+	__trace_stack(&global_trace, flags, 0, preempt_count());
+}
+
 static void ftrace_trace_userstack(struct trace_array *tr,
 				   unsigned long flags, int pc)
 {

Re: [PATCH][GIT PULL] tracing: add trace_stack interface

[Frederic Weisbecker]

On Tue, May 19, 2009 at 08:44:50PM -0400, Steven Rostedt wrote:
> 
> Ingo,
> 
> Please pull the latest tip/tracing/ftrace tree, which can be found at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
> tip/tracing/ftrace
> 
> 
> Steven Rostedt (1):
>       tracing: add trace_stack interface
> 
> ----
>  include/linux/kernel.h |    2 ++
>  kernel/trace/trace.c   |   15 +++++++++++++++
>  2 files changed, 17 insertions(+), 0 deletions(-)
> ---------------------------
> commit b85d1029ba534376d203c3ac83a2e5a4d6876cb6
> Author: Steven Rostedt <srostedt@redhat.com>
> Date:   Tue May 19 18:54:16 2009 -0400
> 
>     tracing: add trace_stack interface
>     
>     This patch adds the global function
>     
>       void trace_stack(void)
>     
>     This allows a developer to find where a function is called. For example,
>     if you want to know who calls __netif_reschedule, you can add
>     
>      static inline void __netif_reschedule(struct Qdisc *q)
>      {
>      	struct softnet_data *sd;
>      	unsigned long flags;
>     
>     +	trace_stack();
>      	local_irq_save(flags);
>      	sd = &__get_cpu_var(softnet_data);
>      	q->next_sched = sd->output_queue;
>     
>     And see the following in the trace output:
>     
>      <= __ftrace_trace_stack
>      <= trace_stack



I guess the depth should begin here :-)



>      <= __netif_schedule
>      <= dev_watchdog
>      <= run_timer_softirq
>      <= __do_softirq
>      <= call_softirq
>      <= do_softirq
>      <= irq_exit
>     
>     Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> 
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 883cd44..347a0f1 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -511,6 +511,7 @@ extern int
>  __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
>  
>  extern void ftrace_dump(void);
> +extern void trace_stack(void);
>  #else
>  static inline void
>  ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
> @@ -531,6 +532,7 @@ ftrace_vprintk(const char *fmt, va_list ap)
>  	return 0;
>  }
>  static inline void ftrace_dump(void) { }
> +static inline void trace_stack(void) { }
>  #endif /* CONFIG_TRACING */
>  
>  /*
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index dd40d23..33ab502 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -1046,6 +1046,21 @@ void __trace_stack(struct trace_array *tr,
>  	__ftrace_trace_stack(tr, flags, skip, pc);
>  }
>  
> +/**
> + * trace_stack - dump the stack into the trace buffer
> + *
> + * Use this to record the stack trace into the ring buffer. If you
> + * want to know a caller of a function, place a call to trace_stack
> + * and the ftrace trace file will display who the callers were.
> + */
> +void trace_stack(void)
> +{
> +	unsigned long flags;
> +
> +	local_save_flags(flags);
> +	__trace_stack(&global_trace, flags, 0, preempt_count());
> +}



Stupidly I use a very similar patch while working on reiserfs
but I forgot to post it.

Another trick is to use trace_printk() combined with:

echo stacktrace > trace_option


Frederic.


>  static void ftrace_trace_userstack(struct trace_array *tr,
>  				   unsigned long flags, int pc)
>  {
> 

[PATCH v2][GIT PULL] tracing: add trace_stack interface

[Steven Rostedt]

Ingo,

I rebased because I forgot to add EXPORT_SYMBOL_GPL.

-- Steve

Please pull the latest tip/tracing/ftrace tree, which can be found at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
tip/tracing/ftrace


Steven Rostedt (1):
      tracing: add trace_stack interface

----
 include/linux/kernel.h |    2 ++
 kernel/trace/trace.c   |   16 ++++++++++++++++
 2 files changed, 18 insertions(+), 0 deletions(-)
---------------------------
commit 9f6b28655254b91c48f684b367ac14bfec0e180a
Author: Steven Rostedt <srostedt@redhat.com>
Date:   Tue May 19 18:54:16 2009 -0400

    tracing: add trace_stack interface
    
    This patch adds the global function
    
      void trace_stack(void)
    
    This allows a developer to find where a function is called. For example,
    if you want to know who calls __netif_reschedule, you can add
    
     static inline void __netif_reschedule(struct Qdisc *q)
     {
     	struct softnet_data *sd;
     	unsigned long flags;
    
    +	trace_stack();
     	local_irq_save(flags);
     	sd = &__get_cpu_var(softnet_data);
     	q->next_sched = sd->output_queue;
    
    And see the following in the trace output:
    
     <= __ftrace_trace_stack
     <= trace_stack
     <= __netif_schedule
     <= dev_watchdog
     <= run_timer_softirq
     <= __do_softirq
     <= call_softirq
     <= do_softirq
     <= irq_exit
    
    Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 883cd44..347a0f1 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -511,6 +511,7 @@ extern int
 __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
 
 extern void ftrace_dump(void);
+extern void trace_stack(void);
 #else
 static inline void
 ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
@@ -531,6 +532,7 @@ ftrace_vprintk(const char *fmt, va_list ap)
 	return 0;
 }
 static inline void ftrace_dump(void) { }
+static inline void trace_stack(void) { }
 #endif /* CONFIG_TRACING */
 
 /*
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dd40d23..7bfd4f2 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1046,6 +1046,22 @@ void __trace_stack(struct trace_array *tr,
 	__ftrace_trace_stack(tr, flags, skip, pc);
 }
 
+/**
+ * trace_stack - dump the stack into the trace buffer
+ *
+ * Use this to record the stack trace into the ring buffer. If you
+ * want to know a caller of a function, place a call to trace_stack
+ * and the ftrace trace file will display who the callers were.
+ */
+void trace_stack(void)
+{
+	unsigned long flags;
+
+	local_save_flags(flags);
+	__trace_stack(&global_trace, flags, 0, preempt_count());
+}
+EXPORT_SYMBOL_GPL(trace_stack);
+
 static void ftrace_trace_userstack(struct trace_array *tr,
 				   unsigned long flags, int pc)
 {

Re: [PATCH][GIT PULL] tracing: add trace_stack interface

[Steven Rostedt]

On Wed, 20 May 2009, Frederic Weisbecker wrote:

> On Tue, May 19, 2009 at 08:44:50PM -0400, Steven Rostedt wrote:
> > 
> > Ingo,
> > 
> > Please pull the latest tip/tracing/ftrace tree, which can be found at:
> > 
> >   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
> > tip/tracing/ftrace
> > 
> > 
> > Steven Rostedt (1):
> >       tracing: add trace_stack interface
> > 
> > ----
> >  include/linux/kernel.h |    2 ++
> >  kernel/trace/trace.c   |   15 +++++++++++++++
> >  2 files changed, 17 insertions(+), 0 deletions(-)
> > ---------------------------
> > commit b85d1029ba534376d203c3ac83a2e5a4d6876cb6
> > Author: Steven Rostedt <srostedt@redhat.com>
> > Date:   Tue May 19 18:54:16 2009 -0400
> > 
> >     tracing: add trace_stack interface
> >     
> >     This patch adds the global function
> >     
> >       void trace_stack(void)
> >     
> >     This allows a developer to find where a function is called. For example,
> >     if you want to know who calls __netif_reschedule, you can add
> >     
> >      static inline void __netif_reschedule(struct Qdisc *q)
> >      {
> >      	struct softnet_data *sd;
> >      	unsigned long flags;
> >     
> >     +	trace_stack();
> >      	local_irq_save(flags);
> >      	sd = &__get_cpu_var(softnet_data);
> >      	q->next_sched = sd->output_queue;
> >     
> >     And see the following in the trace output:
> >     
> >      <= __ftrace_trace_stack
> >      <= trace_stack
> 
> 
> 
> I guess the depth should begin here :-)

Yeah, I thought about that but since it only prints out the stack trace, 
this is sorta the "this is a stack trace" header.
> 
> 
> 
> >      <= __netif_schedule
> >      <= dev_watchdog
> >      <= run_timer_softirq
> >      <= __do_softirq
> >      <= call_softirq
> >      <= do_softirq
> >      <= irq_exit
> >     
> >     Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> > 
> > diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> > index 883cd44..347a0f1 100644
> > --- a/include/linux/kernel.h
> > +++ b/include/linux/kernel.h
> > @@ -511,6 +511,7 @@ extern int
> >  __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
> >  
> >  extern void ftrace_dump(void);
> > +extern void trace_stack(void);
> >  #else
> >  static inline void
> >  ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
> > @@ -531,6 +532,7 @@ ftrace_vprintk(const char *fmt, va_list ap)
> >  	return 0;
> >  }
> >  static inline void ftrace_dump(void) { }
> > +static inline void trace_stack(void) { }
> >  #endif /* CONFIG_TRACING */
> >  
> >  /*
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index dd40d23..33ab502 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -1046,6 +1046,21 @@ void __trace_stack(struct trace_array *tr,
> >  	__ftrace_trace_stack(tr, flags, skip, pc);
> >  }
> >  
> > +/**
> > + * trace_stack - dump the stack into the trace buffer
> > + *
> > + * Use this to record the stack trace into the ring buffer. If you
> > + * want to know a caller of a function, place a call to trace_stack
> > + * and the ftrace trace file will display who the callers were.
> > + */
> > +void trace_stack(void)
> > +{
> > +	unsigned long flags;
> > +
> > +	local_save_flags(flags);
> > +	__trace_stack(&global_trace, flags, 0, preempt_count());
> > +}
> 
> 
> 
> Stupidly I use a very similar patch while working on reiserfs
> but I forgot to post it.
> 
> Another trick is to use trace_printk() combined with:
> 
> echo stacktrace > trace_option

Yeah, but when you are debugging development work, doing that at every 
boot up becomes a pain. You can add it to a rc script but still.

I wrote this because of the development I'm doing in the interrupt 
threads. I was using this a lot to find what is calling what.

-- Steve

Re: [PATCH][GIT PULL] tracing: add trace_stack interface

[Frederic Weisbecker]

On Tue, May 19, 2009 at 09:14:13PM -0400, Steven Rostedt wrote:
> 
> On Wed, 20 May 2009, Frederic Weisbecker wrote:
> 
> > On Tue, May 19, 2009 at 08:44:50PM -0400, Steven Rostedt wrote:
> > > 
> > > Ingo,
> > > 
> > > Please pull the latest tip/tracing/ftrace tree, which can be found at:
> > > 
> > >   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
> > > tip/tracing/ftrace
> > > 
> > > 
> > > Steven Rostedt (1):
> > >       tracing: add trace_stack interface
> > > 
> > > ----
> > >  include/linux/kernel.h |    2 ++
> > >  kernel/trace/trace.c   |   15 +++++++++++++++
> > >  2 files changed, 17 insertions(+), 0 deletions(-)
> > > ---------------------------
> > > commit b85d1029ba534376d203c3ac83a2e5a4d6876cb6
> > > Author: Steven Rostedt <srostedt@redhat.com>
> > > Date:   Tue May 19 18:54:16 2009 -0400
> > > 
> > >     tracing: add trace_stack interface
> > >     
> > >     This patch adds the global function
> > >     
> > >       void trace_stack(void)
> > >     
> > >     This allows a developer to find where a function is called. For example,
> > >     if you want to know who calls __netif_reschedule, you can add
> > >     
> > >      static inline void __netif_reschedule(struct Qdisc *q)
> > >      {
> > >      	struct softnet_data *sd;
> > >      	unsigned long flags;
> > >     
> > >     +	trace_stack();
> > >      	local_irq_save(flags);
> > >      	sd = &__get_cpu_var(softnet_data);
> > >      	q->next_sched = sd->output_queue;
> > >     
> > >     And see the following in the trace output:
> > >     
> > >      <= __ftrace_trace_stack
> > >      <= trace_stack
> > 
> > 
> > 
> > I guess the depth should begin here :-)
> 
> Yeah, I thought about that but since it only prints out the stack trace, 
> this is sorta the "this is a stack trace" header.



Indeed :)


> > 
> > 
> > 
> > >      <= __netif_schedule
> > >      <= dev_watchdog
> > >      <= run_timer_softirq
> > >      <= __do_softirq
> > >      <= call_softirq
> > >      <= do_softirq
> > >      <= irq_exit
> > >     
> > >     Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> > > 
> > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> > > index 883cd44..347a0f1 100644
> > > --- a/include/linux/kernel.h
> > > +++ b/include/linux/kernel.h
> > > @@ -511,6 +511,7 @@ extern int
> > >  __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
> > >  
> > >  extern void ftrace_dump(void);
> > > +extern void trace_stack(void);
> > >  #else
> > >  static inline void
> > >  ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
> > > @@ -531,6 +532,7 @@ ftrace_vprintk(const char *fmt, va_list ap)
> > >  	return 0;
> > >  }
> > >  static inline void ftrace_dump(void) { }
> > > +static inline void trace_stack(void) { }
> > >  #endif /* CONFIG_TRACING */
> > >  
> > >  /*
> > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > > index dd40d23..33ab502 100644
> > > --- a/kernel/trace/trace.c
> > > +++ b/kernel/trace/trace.c
> > > @@ -1046,6 +1046,21 @@ void __trace_stack(struct trace_array *tr,
> > >  	__ftrace_trace_stack(tr, flags, skip, pc);
> > >  }
> > >  
> > > +/**
> > > + * trace_stack - dump the stack into the trace buffer
> > > + *
> > > + * Use this to record the stack trace into the ring buffer. If you
> > > + * want to know a caller of a function, place a call to trace_stack
> > > + * and the ftrace trace file will display who the callers were.
> > > + */
> > > +void trace_stack(void)
> > > +{
> > > +	unsigned long flags;
> > > +
> > > +	local_save_flags(flags);
> > > +	__trace_stack(&global_trace, flags, 0, preempt_count());
> > > +}
> > 
> > 
> > 
> > Stupidly I use a very similar patch while working on reiserfs
> > but I forgot to post it.
> > 
> > Another trick is to use trace_printk() combined with:
> > 
> > echo stacktrace > trace_option
> 
> Yeah, but when you are debugging development work, doing that at every 
> boot up becomes a pain. You can add it to a rc script but still.


Right!


> I wrote this because of the development I'm doing in the interrupt 
> threads. I was using this a lot to find what is calling what.
> 
> -- Steve
> 

Re: [PATCH v2][GIT PULL] tracing: add trace_stack interface

[Frederic Weisbecker]

On Tue, May 19, 2009 at 09:09:40PM -0400, Steven Rostedt wrote:
> 
> Ingo,
> 
> I rebased because I forgot to add EXPORT_SYMBOL_GPL.
> 
> -- Steve
> 
> Please pull the latest tip/tracing/ftrace tree, which can be found at:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
> tip/tracing/ftrace
> 
> 
> Steven Rostedt (1):
>       tracing: add trace_stack interface
> 
> ----
>  include/linux/kernel.h |    2 ++
>  kernel/trace/trace.c   |   16 ++++++++++++++++
>  2 files changed, 18 insertions(+), 0 deletions(-)
> ---------------------------
> commit 9f6b28655254b91c48f684b367ac14bfec0e180a
> Author: Steven Rostedt <srostedt@redhat.com>
> Date:   Tue May 19 18:54:16 2009 -0400
> 
>     tracing: add trace_stack interface
>     
>     This patch adds the global function
>     
>       void trace_stack(void)
>     
>     This allows a developer to find where a function is called. For example,
>     if you want to know who calls __netif_reschedule, you can add
>     
>      static inline void __netif_reschedule(struct Qdisc *q)
>      {
>      	struct softnet_data *sd;
>      	unsigned long flags;
>     
>     +	trace_stack();
>      	local_irq_save(flags);
>      	sd = &__get_cpu_var(softnet_data);
>      	q->next_sched = sd->output_queue;
>     
>     And see the following in the trace output:
>     
>      <= __ftrace_trace_stack
>      <= trace_stack
>      <= __netif_schedule
>      <= dev_watchdog
>      <= run_timer_softirq
>      <= __do_softirq
>      <= call_softirq
>      <= do_softirq
>      <= irq_exit
>     
>     Signed-off-by: Steven Rostedt <rostedt@goodmis.org>


I wanted to use it to get the recursive locking points in reiserfs
but I can't find it.

Has it been merged in -tip ?

Thanks.


 
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 883cd44..347a0f1 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -511,6 +511,7 @@ extern int
>  __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap);
>  
>  extern void ftrace_dump(void);
> +extern void trace_stack(void);
>  #else
>  static inline void
>  ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { }
> @@ -531,6 +532,7 @@ ftrace_vprintk(const char *fmt, va_list ap)
>  	return 0;
>  }
>  static inline void ftrace_dump(void) { }
> +static inline void trace_stack(void) { }
>  #endif /* CONFIG_TRACING */
>  
>  /*
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index dd40d23..7bfd4f2 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -1046,6 +1046,22 @@ void __trace_stack(struct trace_array *tr,
>  	__ftrace_trace_stack(tr, flags, skip, pc);
>  }
>  
> +/**
> + * trace_stack - dump the stack into the trace buffer
> + *
> + * Use this to record the stack trace into the ring buffer. If you
> + * want to know a caller of a function, place a call to trace_stack
> + * and the ftrace trace file will display who the callers were.
> + */
> +void trace_stack(void)
> +{
> +	unsigned long flags;
> +
> +	local_save_flags(flags);
> +	__trace_stack(&global_trace, flags, 0, preempt_count());
> +}
> +EXPORT_SYMBOL_GPL(trace_stack);
> +
>  static void ftrace_trace_userstack(struct trace_array *tr,
>  				   unsigned long flags, int pc)
>  {
> 
> 

Re: [PATCH v2][GIT PULL] tracing: add trace_stack interface

[Steven Rostedt]

On Wed, 3 Jun 2009, Frederic Weisbecker wrote:
> On Tue, May 19, 2009 at 09:09:40PM -0400, Steven Rostedt wrote:
> > 
> > Ingo,
> > 
> > I rebased because I forgot to add EXPORT_SYMBOL_GPL.
> > 
> > -- Steve
> > 
> > Please pull the latest tip/tracing/ftrace tree, which can be found at:
> > 
> >   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
> > tip/tracing/ftrace
> > 
> > 
> > Steven Rostedt (1):
> >       tracing: add trace_stack interface
> > 
> > ----
> >  include/linux/kernel.h |    2 ++
> >  kernel/trace/trace.c   |   16 ++++++++++++++++
> >  2 files changed, 18 insertions(+), 0 deletions(-)
> > ---------------------------
> > commit 9f6b28655254b91c48f684b367ac14bfec0e180a
> > Author: Steven Rostedt <srostedt@redhat.com>
> > Date:   Tue May 19 18:54:16 2009 -0400
> > 
> >     tracing: add trace_stack interface
> >     
> >     This patch adds the global function
> >     
> >       void trace_stack(void)
> >     
> >     This allows a developer to find where a function is called. For example,
> >     if you want to know who calls __netif_reschedule, you can add
> >     
> >      static inline void __netif_reschedule(struct Qdisc *q)
> >      {
> >      	struct softnet_data *sd;
> >      	unsigned long flags;
> >     
> >     +	trace_stack();
> >      	local_irq_save(flags);
> >      	sd = &__get_cpu_var(softnet_data);
> >      	q->next_sched = sd->output_queue;
> >     
> >     And see the following in the trace output:
> >     
> >      <= __ftrace_trace_stack
> >      <= trace_stack
> >      <= __netif_schedule
> >      <= dev_watchdog
> >      <= run_timer_softirq
> >      <= __do_softirq
> >      <= call_softirq
> >      <= do_softirq
> >      <= irq_exit
> >     
> >     Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> 
> 
> I wanted to use it to get the recursive locking points in reiserfs
> but I can't find it.
> 
> Has it been merged in -tip ?
> 

It looks like it hasn't :-(

Luckily, I do not do "git gc" on my relay repo. Otherwise I would have 
totally lost this. (it's no longer in my working repo.) I'll make a branch 
from it now.

I wish merges were OK, because then I would be know if anything is 
missing. When we rebase changes, things can easily get lost.

-- Steve

Re: [PATCH v2][GIT PULL] tracing: add trace_stack interface

[Ingo Molnar]

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> On Tue, May 19, 2009 at 09:09:40PM -0400, Steven Rostedt wrote:
> > 
> > Ingo,
> > 
> > I rebased because I forgot to add EXPORT_SYMBOL_GPL.
> > 
> > -- Steve
> > 
> > Please pull the latest tip/tracing/ftrace tree, which can be found at:
> > 
> >   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
> > tip/tracing/ftrace
> > 
> > 
> > Steven Rostedt (1):
> >       tracing: add trace_stack interface
> > 
> > ----
> >  include/linux/kernel.h |    2 ++
> >  kernel/trace/trace.c   |   16 ++++++++++++++++
> >  2 files changed, 18 insertions(+), 0 deletions(-)
> > ---------------------------
> > commit 9f6b28655254b91c48f684b367ac14bfec0e180a
> > Author: Steven Rostedt <srostedt@redhat.com>
> > Date:   Tue May 19 18:54:16 2009 -0400
> > 
> >     tracing: add trace_stack interface
> >     
> >     This patch adds the global function
> >     
> >       void trace_stack(void)
> >     
> >     This allows a developer to find where a function is called. For example,
> >     if you want to know who calls __netif_reschedule, you can add
> >     
> >      static inline void __netif_reschedule(struct Qdisc *q)
> >      {
> >      	struct softnet_data *sd;
> >      	unsigned long flags;
> >     
> >     +	trace_stack();
> >      	local_irq_save(flags);
> >      	sd = &__get_cpu_var(softnet_data);
> >      	q->next_sched = sd->output_queue;
> >     
> >     And see the following in the trace output:
> >     
> >      <= __ftrace_trace_stack
> >      <= trace_stack
> >      <= __netif_schedule
> >      <= dev_watchdog
> >      <= run_timer_softirq
> >      <= __do_softirq
> >      <= call_softirq
> >      <= do_softirq
> >      <= irq_exit
> >     
> >     Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> 
> 
> I wanted to use it to get the recursive locking points in reiserfs
> but I can't find it.
> 
> Has it been merged in -tip ?

hm, Steve has not sent it along AFAICS. There were no objections 
from me.

	Ingo