All of lore.kernel.org
 help / color / mirror / Atom feed
* [PATCH v2] perf test: Fix test case Merge cpu map
@ 2020-01-20 13:20 Thomas Richter
  2020-01-20 13:20 ` [PATCH v2] perf probe: Add ustring support for perf probe command Thomas Richter
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Thomas Richter @ 2020-01-20 13:20 UTC (permalink / raw)
  To: linux-kernel, linux-perf-users, acme
  Cc: gor, sumanthk, heiko.carstens, Thomas Richter

V2: Added Reviewed-by statement

Commit a2408a70368a ("perf evlist: Maintain evlist->all_cpus")
introduces a test case for cpumap merge operation, see functions
perf_cpu_map__merge() and test__cpu_map_merge().

The test case fails on s390 with this error message:
 [root@m35lp76 perf]# ./perf test -Fvvvvv 52
 52: Merge cpu map                                         :
 --- start ---
 cpumask list: 1-2,4-5,7
 perf: /root/linux/tools/include/linux/refcount.h:131:\
          refcount_sub_and_test: Assertion `!(new > val)' failed.
 Aborted (core dumped)
 [root@m35lp76 perf]#

The root cause is in the function test__cpu_map_merge():
It creates two cpu_maps named 'a' and 'b':

  struct perf_cpu_map *a = perf_cpu_map__new("4,2,1");
  struct perf_cpu_map *b = perf_cpu_map__new("4,5,7");

and creates a third map named 'c' which is the result of
the merge of maps a and b:

  struct perf_cpu_map *c = perf_cpu_map__merge(a, b);

After some verifaction of the merged cpu_map all three
of them are have their reference count reduced and are
freed:

   perf_cpu_map__put(a); (1)
   perf_cpu_map__put(b);
   perf_cpu_map__put(c);

The release of perf_cpu_map__put(a) is wrong. The map
is already released and free'ed as part of the function

  perf_cpu_map__merge(struct perf_cpu_map *orig,
  |	              struct perf_cpu_map *other)
  +--> perf_cpu_map__put(orig);
       |
       +--> cpu_map__delete(orig)

At the end perf_cpu_map_put() is called for map 'orig'
alias 'a' and since the reference count is 1, the map
is deleted, as can be seen by the following gdb trace:

 (gdb) where
 #0  tcache_put (tc_idx=0, chunk=0x156cc30) at malloc.c:2940
 #1  _int_free (av=0x3fffd49ee80 <main_arena>, p=0x156cc30,
		     have_lock=<optimized out>) at malloc.c:4222
 #2  0x00000000012d5e78 in cpu_map__delete (map=0x156cc40) at cpumap.c:31
 #3  0x00000000012d5f7a in perf_cpu_map__put (map=0x156cc40) at cpumap.c:45
 #4  0x00000000012d723a in perf_cpu_map__merge (orig=0x156cc40,
     other=0x156cc60) at cpumap.c:343
 #5  0x000000000110cdd0 in test__cpu_map_merge (
     test=0x14ea6c8 <generic_tests+2856>, subtest=-1) at tests/cpumap.c:128

Thus the perf_cpu_map__put(a) (see (1) above) frees map 'a'
a second time and causes the failure. Fix this be removing that
function call.

Output after:
  [root@m35lp76 perf]# ./perf test -Fvvvvv 52
  52: Merge cpu map                                         :
  --- start ---
  cpumask list: 1-2,4-5,7
  ---- end ----
  Merge cpu map: Ok
  [root@m35lp76 perf]#

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
---
 tools/perf/tests/cpumap.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tools/perf/tests/cpumap.c b/tools/perf/tests/cpumap.c
index 4ac56741ac5f..29c793ac7d10 100644
--- a/tools/perf/tests/cpumap.c
+++ b/tools/perf/tests/cpumap.c
@@ -131,7 +131,6 @@ int test__cpu_map_merge(struct test *test __maybe_unused, int subtest __maybe_un
 	TEST_ASSERT_VAL("failed to merge map: bad nr", c->nr == 5);
 	cpu_map__snprint(c, buf, sizeof(buf));
 	TEST_ASSERT_VAL("failed to merge map: bad result", !strcmp(buf, "1-2,4-5,7"));
-	perf_cpu_map__put(a);
 	perf_cpu_map__put(b);
 	perf_cpu_map__put(c);
 	return 0;
-- 
2.21.0

^ permalink raw reply related	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-02-05 15:45 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-01-20 13:20 [PATCH v2] perf test: Fix test case Merge cpu map Thomas Richter
2020-01-20 13:20 ` [PATCH v2] perf probe: Add ustring support for perf probe command Thomas Richter
2020-02-05 15:45   ` [tip: perf/urgent] " tip-bot2 for Thomas Richter
2020-01-20 13:20 ` [PATCH v2] perf test: Fix test trace+probe_vfs_getname.sh Thomas Richter
2020-01-31  8:36   ` Arnaldo Carvalho de Melo
2020-02-05 15:45 ` [tip: perf/urgent] perf test: Fix test case Merge cpu map tip-bot2 for Thomas Richter

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.