Messages in this thread | | | Date | Mon, 11 Oct 2021 16:45:10 +0200 | From | Peter Zijlstra <> | Subject | Re: [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 :-)
| |