Commit 895e3b06 authored Mar 26, 2018 by Arnaldo Carvalho de Melo

perf mmap: Be consistent when checking for an unmaped ring buffer

The previous patch is insufficient to cure the reported 'perf trace'
segfault, as it only cures the perf_mmap__read_done() case, moving the
segfault to perf_mmap__read_init() functio, fix it by doing the same
refcount check.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 8872481b ("perf mmap: Introduce perf_mmap__read_init()")
Link: https://lkml.kernel.org/r/20180326144127.GF18897@kernel.org

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent f58385f6

tools/perf/util/mmap.c

+12 −1

Original line number	Diff line number	Diff line
		@@ -234,7 +234,7 @@ static int overwrite_rb_find_range(void buf, int mask, u64 start, u64 *end)
		/*
		* Report the start and end of the available data in ringbuffer
		*/
		int perf_mmap__read_init(struct perf_mmap *md)
		static int __perf_mmap__read_init(struct perf_mmap *md)
		{
		u64 head = perf_mmap__read_head(md);
		u64 old = md->prev;
		@@ -268,6 +268,17 @@ int perf_mmap__read_init(struct perf_mmap *md)
		return 0;
		}

		int perf_mmap__read_init(struct perf_mmap *map)
		{
		/*
		* Check if event was unmapped due to a POLLHUP/POLLERR.
		*/
		if (!refcount_read(&map->refcnt))
		return -ENOENT;

		return __perf_mmap__read_init(map);
		}

		int perf_mmap__push(struct perf_mmap md, void to,
		int push(void to, void buf, size_t size))
		{