[PATCH 3/4] perf cpu_map: Fix core dump caused by per-socket/core system-wide stat

From: Arnaldo Carvalho de Melo
Date: Tue Oct 20 2015 - 16:25:25 EST


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>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1444388363-35936-1-git-send-email-kan.liang@xxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
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 b36845347f01..aa6b490aa471 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -285,7 +285,7 @@ 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);
*res = c;
return 0;
}
--
2.1.0

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