linux-kernel - [PATCH 1/3] perf tools: Avoid deadlock when map

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Date:	Wed, 19 Aug 2015 17:29:19 +0300
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
	Jiri Olsa <jolsa@...hat.com>, Jiri Olsa <jolsa@...nel.org>
Cc:	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	mingo@...nel.org
Subject: [PATCH 1/3] perf tools: Avoid deadlock when map_groups are broken

Attempting to clone map groups onto themselves will deadlock.
It only happens because of other bugs, but the code should
protect itself anyway.

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 tools/perf/util/thread.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 28c4b746baa1..471102554a78 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -191,6 +191,12 @@ static int thread__clone_map_groups(struct thread *thread,
 	if (thread->pid_ == parent->pid_)
 		return 0;
 
+	if (thread->mg == parent->mg) {
+		dump_printf("broken map groups on thread %d/%d parent %d/%d\n",
+			    thread->pid_, thread->tid, parent->pid_, parent->tid);
+		return 0;
+	}
+
 	/* But this one is new process, copy maps. */
 	for (i = 0; i < MAP__NR_TYPES; ++i)
 		if (map_groups__clone(thread->mg, parent->mg, i) < 0)
-- 
1.9.1

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