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perf mmap: Fix accessing unmapped mmap in perf_mmap__read_done()

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There is a segmentation fault when running 'perf trace'. For example:

  [root@jouet e]# perf trace -e *chdir -o /tmp/bla perf report --ignore-vmlinux -i ../perf.data

The perf_mmap__consume() could unmap the mmap. It needs to check the
refcnt in perf_mmap__read_done().

Reported-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: ee023de05f ("perf mmap: Introduce perf_mmap__read_done()")
Link: http://lkml.kernel.org/r/1522071729-16776-1-git-send-email-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Kan Liang 2018-03-26 09:42:09 -04:00 committed by Arnaldo Carvalho de Melo
parent b4c786e5aa
commit f58385f629
1 changed files with 6 additions and 0 deletions
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6
tools/perf/util/mmap.c
View file

@ -317,5 +317,11 @@ int perf_mmap__push(struct perf_mmap *md, void *to,
*/
void perf_mmap__read_done(struct perf_mmap *map)
{
/*
* Check if event was unmapped due to a POLLHUP/POLLERR.
*/
if (!refcount_read(&map->refcnt))
return;
map->prev = perf_mmap__read_head(map);
}