Messages in this thread | | | Date | Sun, 16 Nov 2008 07:49:48 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 3/4] tracing/branch-tracer: Fix a trace recursion on branch tracer |
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* Frédéric Weisbecker <fweisbec@gmail.com> wrote:
> 2008/11/16 Ingo Molnar <mingo@elte.hu>: > > > > * Frederic Weisbecker <fweisbec@gmail.com> wrote: > > > >> Impact: Make the branch tracer use raw irq save/restore > >> > >> When the branch tracer inserts an event through > >> probe_likely_condition(), it calls local_irq_save() and then results > >> in a trace recursion. > >> > >> local_irq_save() -> trace_hardirqs_off() -> trace_hardirqs_off_caller() > >> -> unlikely() > >> > >> The trace_branch.c file is protected by DISABLE_BRANCH_PROFILING but > >> that doesn't prevent from external call to functions that use > >> unlikely(). > >> > >> My box crashed each time I tried to set this tracer (sudden and hard > >> reboot). > > > > So this patch fixes that problem, or are there other problems left? > > > > Ingo > > > > > I forgot to answer to all. Yes that fixes it.
cool - i was seeing the crashes too in automated testing, just havent had time to debug it yet.
One small detail:
Regarding the "Impact" line, it's cool that you started adding them. I'd like to ask you to tweak them a little bit in the future: please try to describe the "practical impact" via them - not just a repetition of the source code change that the patch does.
For example, for this patch, instead of this impact-line:
Impact: Make the branch tracer use raw irq save/restore
a better one is:
Impact: fix crash when enabling the branch-tracer
(i changed it in this patch, no need to resubmit. And it's not well documented anyway.)
Thanks,
Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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