lkml.org 
[lkml]   [2008]   [Nov]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] tracing/function-return-tracer: Add a barrier to ensure return stack index is incremented in memory

On Sat, 15 Nov 2008, Frederic Weisbecker wrote:

> Impact: Fix possible race condition in ftrace function return tracer
>
> This fixes a possible race condition if index incrementation
> is not immediately flushed in memory.
>
> Thanks for Andi Kleen and Steven Rostedt for pointing out this issue
> and give me this solution.
>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>

Acked-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve

> Cc: Andi Kleen <andi@firstfloor.org>
> ---
> arch/x86/kernel/ftrace.c | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index fe83273..db25236 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -56,6 +56,7 @@ static int push_return_trace(unsigned long ret, unsigned long long time,
> return -EBUSY;
>
> index = ++ti->curr_ret_stack;
> + barrier();
> ti->ret_stack[index].ret = ret;
> ti->ret_stack[index].func = func;
> ti->ret_stack[index].calltime = time;



\
 
 \ /
  Last update: 2008-11-15 02:51    [W:0.043 / U:1.708 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site