linux-kernel - [PATCH 1/3] perf: __perf_evlist__mmap: Fix errno value on failed map.

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Date:	Mon, 19 Dec 2011 08:39:30 -0500
From:	Nelson Elhage <nelhage@...hage.com>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Paul Mackerras <paulus@...ba.org>, Ingo Molnar <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	linux-kernel@...r.kernel.org, Nelson Elhage <nelhage@...hage.com>
Subject: [PATCH 1/3] perf: __perf_evlist__mmap: Fix errno value on failed map.

On failure, perf_evlist__mmap_per_{cpu,thread} will try to munmap()
every map that doesn't have a NULL base. This will fail with EINVAL if
one of them has base == MAP_FAILED, clobbering errno, so that
perf_evlist__map will return EINVAL on any failure regardless of the
root cause.

Fix this by resetting failed maps to a NULL base.

Signed-off-by: Nelson Elhage <nelhage@...hage.com>
---
 tools/perf/util/evlist.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index fbb4b4a..271c849 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -298,8 +298,10 @@ static int __perf_evlist__mmap(struct perf_evlist *evlist,
 	evlist->mmap[idx].mask = mask;
 	evlist->mmap[idx].base = mmap(NULL, evlist->mmap_len, prot,
 				      MAP_SHARED, fd, 0);
-	if (evlist->mmap[idx].base == MAP_FAILED)
+	if (evlist->mmap[idx].base == MAP_FAILED) {
+		evlist->mmap[idx].base = NULL;
 		return -1;
+	}
 
 	perf_evlist__add_pollfd(evlist, fd);
 	return 0;
-- 
1.7.4.41.g50b8f

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