RE: [PATCH 1/1] perf,tools: fix core dump caused by per-socket/core system-wide stat

[Liang, Kan]

Hi Arnaldo

Here is one more fix for perf/core need to be pulled.

Thanks,
Kan

> 
> On Fri, Oct 09, 2015 at 06:59:23AM -0400, kan.liang@xxxxxxxxx wrote:
> > From: Kan Liang <kan.liang@xxxxxxxxx>
> >
> > Perf will core dump if --per-socket/core -a are applied for perf stat.
> >
> > The root cause is that cpu_map__build_map set refcnt of evlist's
> > cpu_map to 1.
> > It should set refcnt for the newly created cpu_map, not evlist's
> > cpu_map.
> >
> > Here is the example:
> >
> > perf stat -e cycles --per-socket -a sleep 1
> >
> >  Performance counter stats for 'system wide':
> >
> > S0       36         30,196,257      cycles
> > S1       28         15,823,536      cycles
> >
> >        1.001126828 seconds time elapsed
> >
> > *** Error in `./perf': corrupted double-linked list:
> > 0x00000000021f9090
> > ***
> > ======= Backtrace: =========
> > /lib64/libc.so.6[0x3002e7bbe7]
> > /lib64/libc.so.6[0x3002e7d2b5]
> > ./perf(perf_evsel__delete+0x28)[0x485bdd]
> > ./perf[0x4800e8]
> > ./perf(perf_evlist__delete+0x5e)[0x482cd5]
> > ./perf(cmd_stat+0xf25)[0x432328]
> > ./perf[0x4768e0]
> > ./perf[0x476ad6]
> > ./perf[0x476b41]
> > ./perf(main+0x1d0)[0x476db2]
> > /lib64/libc.so.6(__libc_start_main+0xf5)[0x3002e21b45]
> > ./perf[0x4202c5]
> >
> > Signed-off-by: Kan Liang <kan.liang@xxxxxxxxx>
> > ---
> >  tools/perf/util/cpumap.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c index
> > c51c29f..dfc1f0b 100644
> > --- a/tools/perf/util/cpumap.c
> > +++ b/tools/perf/util/cpumap.c
> > @@ -284,7 +284,7 @@ static int cpu_map__build_map(struct cpu_map
> *cpus, struct cpu_map **res,
> >  	/* ensure we process id in increasing order */
> >  	qsort(c->map, c->nr, sizeof(int), cmp_ids);
> >
> > -	atomic_set(&cpus->refcnt, 1);
> > +	atomic_set(&c->refcnt, 1);
> 
> ouch ;-)
> 
> Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> 
> thanks,
> jirka
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