Commit e10e4ef6 authored May 25, 2016 by Wang Nan Committed by Arnaldo Carvalho de Melo May 30, 2016

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



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>

parent f3058a1c

tools/perf/util/evlist.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -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];

		BUG_ON(md->base && atomic_read(&md->refcnt) == 0);

		if (atomic_dec_and_test(&evlist->mmap[idx].refcnt))
		if (atomic_dec_and_test(&md->refcnt))
		__perf_evlist__munmap(evlist, idx);
		}

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