Messages in this thread | | | From | Arnaldo Carvalho de Melo <> | Date | Thu, 7 Mar 2019 16:26:39 -0300 | Subject | Re: [PATCH] perf/core: restore mmap record type correctly |
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Em Thu, Mar 07, 2019 at 08:09:39PM +0100, Peter Zijlstra escreveu: > On Thu, Mar 07, 2019 at 04:03:30PM -0300, Arnaldo Carvalho de Melo wrote: > > Em Thu, Mar 07, 2019 at 10:52:33AM -0800, Stephane Eranian escreveu: > > > On mmap(), perf_events generates a RECORD_MMAP record and then checks > > > which events are interested in this record. There are currently 2 versions > > > of mmap records: RECORD_MMAP and RECORD_MMAP2. MMAP2 is larger. The event > > > configuration controls which version the user level tool accepts. If the > > > event->attr.mmap2=1 field then MMAP2 record is returned. The > > > perf_event_mmap_output() takes care of this. It checks attr->mmap2 and corrects > > > the record fields before putting it in the sampling buffer of the event. > > > At the end the function restores the modified MMAP record fields.
> > > The problem is that the function restores the size but not the > > > type. Thus, if a subsequent event only accepts MMAP type, then it would > > > instead receive an MMAP2 record with a size of MMAP record.
> > > This patch fixes the problem by restoring the record type on exit.
> > Right, simple enough, bug fixed, Peter, I'm taking this one, ok?
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
BTW, added:
Fixes: 13d7a2410fa6 ("perf: Add attr->mmap2 attribute to an event")
For the stable guys to pick this up. Please try to add the fixes tag in the future.
Thanks,
- Arnaldo
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