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

[kan . liang]

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);
 	*res = c;
 	return 0;
 }
-- 
1.8.3.1

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