[PATCH AUTOSEL 4.19 31/49] perf namespace: Protect reading thread's namespace

Sasha Levin
2019-06-08T11:44:14Z

From: Namhyung Kim <namhyung@kernel.org>

[ Upstream commit 6584140ba9e6762dd7ec73795243289b914f31f9 ]

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>
Cc: Hari Bathini <hbathini@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Krister Johansen <kjlx@templeofstupid.com>
Link: http://lkml.kernel.org/r/20190522053250.207156-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@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 2048d393ece6..56007a7e0b4d 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -128,7 +128,7 @@ 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;
@@ -136,10 +136,21 @@ 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)
--
2.20.1