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perf evlist: Check 'base' pointer before checking refcnt when put a mmap

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evlist->mmap[i]->refcnt could be 0 if an evlist has no evsel or if all
evsels don't match the evlist during mmap. For example, when all evsels
are overwritable but the evlist itself is normal. To avoid crashing,
perf should check 'base' pointer before checking refcnt, and raise bug
only when base is not NULL.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1464183898-174512-2-git-send-email-wangnan0@huawei.com
[ Renamed 'mmap' variable, it is reserved in old distros such as Ubuntu 12.04, breaking the build ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Wang Nan 2016-05-25 13:44:49 +00:00 committed by Arnaldo Carvalho de Melo
parent f3058a1c19
commit e10e4ef63b
1 changed files with 4 additions and 2 deletions
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6
tools/perf/util/evlist.c
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@ -856,9 +856,11 @@ static void perf_evlist__mmap_get(struct perf_evlist *evlist, int idx)
static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx)
{
BUG_ON(atomic_read(&evlist->mmap[idx].refcnt) == 0);
struct perf_mmap *md = &evlist->mmap[idx];
if (atomic_dec_and_test(&evlist->mmap[idx].refcnt))
BUG_ON(md->base && atomic_read(&md->refcnt) == 0);
if (atomic_dec_and_test(&md->refcnt))
__perf_evlist__munmap(evlist, idx);
}