lkml.org 
[lkml]   [2021]   [Oct]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RESEND PATCH v2] trace: prevent preemption in perf_ftrace_function_call()
On Mon, Oct 11, 2021 at 05:39:32PM +0800, 王贇 wrote:
>
>
> On 2021/10/11 下午4:48, Peter Zijlstra wrote:
> > On Mon, Oct 11, 2021 at 10:32:46AM +0200, Peter Zijlstra wrote:
> >> diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h
> >> index a9f9c5714e65..ca12e2d8e060 100644
> >> --- a/include/linux/trace_recursion.h
> >> +++ b/include/linux/trace_recursion.h
> >> @@ -214,7 +214,14 @@ static __always_inline void trace_clear_recursion(int bit)
> >> static __always_inline int ftrace_test_recursion_trylock(unsigned long ip,
> >> unsigned long parent_ip)
> >> {
> >> - return trace_test_and_set_recursion(ip, parent_ip, TRACE_FTRACE_START, TRACE_FTRACE_MAX);
> >> + bool ret;
> >> +
> >> + preempt_disable_notrace();
> >> + ret = trace_test_and_set_recursion(ip, parent_ip, TRACE_FTRACE_START, TRACE_FTRACE_MAX);
> >> + if (!ret)
> >> + preempt_enable_notrace();
> >> +
> >> + return ret;
> >> }
> >>
> >> /**
> >
> > Oh, I might've gotten that wrong, I assumed regular trylock semantics,
> > but it doesn't look like that's right.
>
> I will use bit instead ret and give some testing :-)
>
> BTW, would you prefer to merge these changes into this patch or maybe send
> another patch with your suggested-by?

Yeah, please send another patch; once you've confirmed it actually works
etc.. I did this before waking (as evidence per the above), who knows
what else I did wrong :-)

\
 
 \ /
  Last update: 2021-10-11 16:47    [W:0.046 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site