linux-kernel - Re: [RFC patch 17/41] tracing: Make stack_trace

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Date:   Thu, 11 Apr 2019 09:19:42 +0900
From:   AKASHI Takahiro <takahiro.akashi@...aro.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        Alexander Potapenko <glider@...gle.com>
Subject: Re: [RFC patch 17/41] tracing: Make stack_trace_print() static and
 rename it

On Wed, Apr 10, 2019 at 08:47:03AM -0400, Steven Rostedt wrote:
> On Wed, 10 Apr 2019 12:28:11 +0200
> Thomas Gleixner <tglx@...utronix.de> wrote:
> 
> > It's only used in the source file where it is defined and it's using the
> > stack_trace_ namespace. Rename it to free it up for stack trace related
> > functions.
> > 
> 
> Can you put it back to its original name "print_max_stack()" which was
> changed by this commit:
> 
> bb99d8ccec7 ("tracing: Allow arch-specific stack tracer")
> 
> I actually want to do a clean up and remove all "trace_" functions that
> are not a tracepoint. It's getting confusing to see a "trace_..." and
> search for the corresponding TRACE_EVENT() macro and not being able to
> find it.
> 
> Hmm, I'm not sure why Akashi changed that function to be global in the
> first place. It looks like only check_stack() needed to be changed.
> 
> Akashi?

Well, as indicated in the commit log, I implemented arch64-specific
check_stack() and used stack_trace_print() in there. At the end of the day,
however, only the first part of my patch set[1], including 'bb99d8ccec7',
was merged. Since then the said function was never used outside of the file.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-December/393716.html

Thanks,
-Takahiro Akashi

> -- Steve
> 
> 
> > Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> > Cc: Steven Rostedt <rostedt@...dmis.org>
> > ---
> >  include/linux/ftrace.h     |    1 -
> >  kernel/trace/trace_stack.c |    4 ++--
> >  2 files changed, 2 insertions(+), 3 deletions(-)
> > 
> > --- a/include/linux/ftrace.h
> > +++ b/include/linux/ftrace.h
> > @@ -251,7 +251,6 @@ extern unsigned long stack_trace_max_siz
> >  extern arch_spinlock_t stack_trace_max_lock;
> >  
> >  extern int stack_tracer_enabled;
> > -void stack_trace_print(void);
> >  int
> >  stack_trace_sysctl(struct ctl_table *table, int write,
> >  		   void __user *buffer, size_t *lenp,
> > --- a/kernel/trace/trace_stack.c
> > +++ b/kernel/trace/trace_stack.c
> > @@ -41,7 +41,7 @@ static DEFINE_MUTEX(stack_sysctl_mutex);
> >  int stack_tracer_enabled;
> >  static int last_stack_tracer_enabled;
> >  
> > -void stack_trace_print(void)
> > +static void trace_stack_trace_print(void)
> >  {
> >  	long i;
> >  	int size;
> > @@ -179,7 +179,7 @@ check_stack(unsigned long ip, unsigned l
> >  	stack_trace_max.nr_entries = x;
> >  
> >  	if (task_stack_end_corrupted(current)) {
> > -		stack_trace_print();
> > +		trace_stack_trace_print();
> >  		BUG();
> >  	}
> >  
> > 
>