diff options
| author | Masami Hiramatsu (Google) <mhiramat@kernel.org> | 2022-09-04 13:12:29 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-09-15 11:30:02 +0200 |
| commit | 75082adeb414113ce1afa710c50f8dacdd8245b0 (patch) | |
| tree | 8d2a2c0b9b85a9ecce80f795fbcdae8fb0de72aa /kernel | |
| parent | 98e8e67395cc6d0cdf3a771f86ea42d0ee6e59dd (diff) | |
tracing: Fix to check event_mutex is held while accessing trigger list
commit cecf8e128ec69149fe53c9a7bafa505a4bee25d9 upstream.
Since the check_user_trigger() is called outside of RCU
read lock, this list_for_each_entry_rcu() caused a suspicious
RCU usage warning.
# echo hist:keys=pid > events/sched/sched_stat_runtime/trigger
# cat events/sched/sched_stat_runtime/trigger
[ 43.167032]
[ 43.167418] =============================
[ 43.167992] WARNING: suspicious RCU usage
[ 43.168567] 5.19.0-rc5-00029-g19ebe4651abf #59 Not tainted
[ 43.169283] -----------------------------
[ 43.169863] kernel/trace/trace_events_trigger.c:145 RCU-list traversed in non-reader section!!
...
However, this file->triggers list is safe when it is accessed
under event_mutex is held.
To fix this warning, adds a lockdep_is_held check to the
list_for_each_entry_rcu().
Link: https://lkml.kernel.org/r/166226474977.223837.1992182913048377113.stgit@devnote2
Cc: stable@vger.kernel.org
Fixes: 7491e2c44278 ("tracing: Add a probe that attaches to trace events")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace_events_trigger.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c index 67c7979c40c0..106f9813841a 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -128,7 +128,8 @@ static bool check_user_trigger(struct trace_event_file *file) { struct event_trigger_data *data; - list_for_each_entry_rcu(data, &file->triggers, list) { + list_for_each_entry_rcu(data, &file->triggers, list, + lockdep_is_held(&event_mutex)) { if (data->flags & EVENT_TRIGGER_FL_PROBE) continue; return true; |