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From: Namhyung Kim <namhyung@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>, Jiri Olsa <jolsa@redhat.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Krister Johansen <kjlx@templeofstupid.com>,
	Hari Bathini <hbathini@linux.vnet.ibm.com>
Subject: [PATCH 1/3] perf tools: Protect reading thread's namespace
Date: Wed, 22 May 2019 14:32:48 +0900
Message-ID: <20190522053250.207156-2-namhyung@kernel.org> (raw)
In-Reply-To: <20190522053250.207156-1-namhyung@kernel.org>

It seems that the current code lacks holding the namespace lock in
thread__namespaces().  Otherwise it can see inconsistent results.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/util/thread.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index 403045a2bbea..b413ba5b9835 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -133,7 +133,7 @@ void thread__put(struct thread *thread)
 	}
 }
 
-struct namespaces *thread__namespaces(const struct thread *thread)
+static struct namespaces *__thread__namespaces(const struct thread *thread)
 {
 	if (list_empty(&thread->namespaces_list))
 		return NULL;
@@ -141,10 +141,21 @@ struct namespaces *thread__namespaces(const struct thread *thread)
 	return list_first_entry(&thread->namespaces_list, struct namespaces, list);
 }
 
+struct namespaces *thread__namespaces(const struct thread *thread)
+{
+	struct namespaces *ns;
+
+	down_read((struct rw_semaphore *)&thread->namespaces_lock);
+	ns = __thread__namespaces(thread);
+	up_read((struct rw_semaphore *)&thread->namespaces_lock);
+
+	return ns;
+}
+
 static int __thread__set_namespaces(struct thread *thread, u64 timestamp,
 				    struct namespaces_event *event)
 {
-	struct namespaces *new, *curr = thread__namespaces(thread);
+	struct namespaces *new, *curr = __thread__namespaces(thread);
 
 	new = namespaces__new(event);
 	if (!new)
-- 
2.21.0.1020.gf2820cf01a-goog


  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-22  5:32 [PATCH 0/3] perf tools: Assorted fixes and cleanups for namespace events Namhyung Kim
2019-05-22  5:32 ` Namhyung Kim [this message]
2019-05-22 13:18   ` [PATCH 1/3] perf tools: Protect reading thread's namespace Arnaldo Carvalho de Melo
2019-05-23  2:36     ` Namhyung Kim
2019-05-27  6:11       ` [PATCH 4/3] perf tools: Remove const from thread read accessors Namhyung Kim
2019-05-27 14:15         ` Arnaldo Carvalho de Melo
2019-05-30  8:07         ` [tip:perf/core] " tip-bot for Namhyung Kim
2019-05-28 21:27   ` [tip:perf/urgent] perf namespace: Protect reading thread's namespace tip-bot for Namhyung Kim
2019-05-22  5:32 ` [PATCH 2/3] perf tools: Add missing swap ops for namespace events Namhyung Kim
2019-05-22 13:23   ` Arnaldo Carvalho de Melo
2019-05-28 21:28   ` [tip:perf/urgent] perf session: " tip-bot for Namhyung Kim
2019-05-22  5:32 ` [PATCH 3/3] perf top: Enable --namespaces option Namhyung Kim
2019-05-22 13:24   ` Arnaldo Carvalho de Melo
2019-05-23  2:42     ` Namhyung Kim
2019-05-30  8:06   ` [tip:perf/core] perf top: Add " tip-bot for Namhyung Kim

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