From 895e3b06fc2ce438adc62cb13d31ea001dcfda16 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Mon, 26 Mar 2018 11:42:15 -0300 Subject: 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 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(-) (limited to 'tools/perf') 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)) { -- cgit v1.2.3-59-g8ed1b