From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnaldo Carvalho de Melo Subject: [PATCH 3/8] perf mmap: Be consistent when checking for an unmaped ring buffer Date: Wed, 28 Mar 2018 15:49:14 -0300 Message-ID: <20180328184919.32287-4-acme@kernel.org> References: <20180328184919.32287-1-acme@kernel.org> Return-path: In-Reply-To: <20180328184919.32287-1-acme@kernel.org> Sender: linux-kernel-owner@vger.kernel.org To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Arnaldo Carvalho de Melo , Adrian Hunter , David Ahern , Jiri Olsa , Kan Liang , Namhyung Kim , Wang Nan List-Id: linux-perf-users.vger.kernel.org From: Arnaldo Carvalho de Melo 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 Cc: Arnaldo Carvalho de Melo Cc: David Ahern Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Cc: Wang Nan Fixes: 8872481bd048 ("perf mmap: Introduce perf_mmap__read_init()") Link: https://lkml.kernel.org/r/20180326144127.GF18897@kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/mmap.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c index f6cfc52ff1fe..fc832676a798 100644 --- a/tools/perf/util/mmap.c +++ b/tools/perf/util/mmap.c @@ -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)) { -- 2.14.3