Messages in this thread | | | Date | Fri, 30 Oct 2020 08:30:39 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH 1/9] ftrace: Move the recursion testing into global headers |
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On Fri, 30 Oct 2020 10:13:50 +0100 (CET) Miroslav Benes <mbenes@suse.cz> wrote:
> how does this work in case of NMI? trace_get_context_bit() returns 0 (it > does not change later in the patch set). "start" in > trace_test_and_set_recursion() is 0 zero too as used later in the patch > set by ftrace_test_recursion_trylock(). So trace_test_and_set_recursion() > returns 0. That is perfectly sane, but then... > > > +static __always_inline void trace_clear_recursion(int bit) > > +{ > > + unsigned int val = current->trace_recursion; > > + > > + if (!bit) > > + return; > > ... the bit is not cleared here.
Yeah, I found that and fixed it yesterday, which discovered stack overflow in perf:
https://lore.kernel.org/r/20201030002722.766a22df@oasis.local.home
There's another bug that causes a false positive during interrupt context transition. I have a fix for that too.
-- Steve
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