releases/4.19.54/perf-namespace-protect-reading-thread-s-namespace.patch

   1 From d3f7cba32820e241abf2f94ada3ce83ad96b04e4 Mon Sep 17 00:00:00 2001
   2 From: Namhyung Kim <namhyung@kernel.org>
   3 Date: Wed, 22 May 2019 14:32:48 +0900
   4 Subject: perf namespace: Protect reading thread's namespace
   5
   6 [ Upstream commit 6584140ba9e6762dd7ec73795243289b914f31f9 ]
   7
   8 It seems that the current code lacks holding the namespace lock in
   9 thread__namespaces().  Otherwise it can see inconsistent results.
  10
  11 Signed-off-by: Namhyung Kim <namhyung@kernel.org>
  12 Cc: Hari Bathini <hbathini@linux.vnet.ibm.com>
  13 Cc: Jiri Olsa <jolsa@redhat.com>
  14 Cc: Krister Johansen <kjlx@templeofstupid.com>
  15 Link: http://lkml.kernel.org/r/20190522053250.207156-2-namhyung@kernel.org
  16 Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
  17 Signed-off-by: Sasha Levin <sashal@kernel.org>
  18 ---
  19  tools/perf/util/thread.c | 15 +++++++++++++--
  20  1 file changed, 13 insertions(+), 2 deletions(-)
  21
  22 diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
  23 index 2048d393ece6..56007a7e0b4d 100644
  24 --- a/tools/perf/util/thread.c
  25 +++ b/tools/perf/util/thread.c
  26 @@ -128,7 +128,7 @@ void thread__put(struct thread *thread)
  27         }
  28  }
  29
  30 -struct namespaces *thread__namespaces(const struct thread *thread)
  31 +static struct namespaces *__thread__namespaces(const struct thread *thread)
  32  {
  33         if (list_empty(&thread->namespaces_list))
  34                 return NULL;
  35 @@ -136,10 +136,21 @@ struct namespaces *thread__namespaces(const struct thread *thread)
  36         return list_first_entry(&thread->namespaces_list, struct namespaces, list);
  37  }
  38
  39 +struct namespaces *thread__namespaces(const struct thread *thread)
  40 +{
  41 +       struct namespaces *ns;
  42 +
  43 +       down_read((struct rw_semaphore *)&thread->namespaces_lock);
  44 +       ns = __thread__namespaces(thread);
  45 +       up_read((struct rw_semaphore *)&thread->namespaces_lock);
  46 +
  47 +       return ns;
  48 +}
  49 +
  50  static int __thread__set_namespaces(struct thread *thread, u64 timestamp,
  51                                     struct namespaces_event *event)
  52  {
  53 -       struct namespaces *new, *curr = thread__namespaces(thread);
  54 +       struct namespaces *new, *curr = __thread__namespaces(thread);
  55
  56         new = namespaces__new(event);
  57         if (!new)
  58 --
  59 2.20.1
  60