[tip:tracing/core] tracing/events: fix concurrent access to ftrace_events list, fix

[tip-bot for Li Zefan]

Commit-ID:  d94fc523f3c35bd8013f04827e94756cbc0212f4
Gitweb:     http://git.kernel.org/tip/d94fc523f3c35bd8013f04827e94756cbc0212f4
Author:     Li Zefan <lizf@xxxxxxxxxxxxxx>
AuthorDate: Thu, 7 May 2009 15:11:15 +0800
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 7 May 2009 10:07:28 +0200

tracing/events: fix concurrent access to ftrace_events list, fix

In filter_add_subsystem_pred() we should release event_mutex before
calling filter_free_subsystem_preds(), since both functions hold
event_mutex.

[ Impact: fix deadlock when writing invalid pred into subsystem filter ]

Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: tzanussi@xxxxxxxxx
Cc: a.p.zijlstra@xxxxxxxxx
Cc: fweisbec@xxxxxxxxx
Cc: rostedt@xxxxxxxxxxx
LKML-Reference: <4A028993.7020509@xxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
 kernel/trace/trace_events_filter.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 8c62e5b..85ad6a8 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -636,14 +636,15 @@ static int filter_add_subsystem_pred(struct filter_parse_state *ps,
 
 		err = filter_add_pred(ps, call, pred);
 		if (err) {
+			mutex_unlock(&event_mutex);
 			filter_free_subsystem_preds(system);
 			parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
-			break;
+			goto out;
 		}
 		replace_filter_string(call->filter, filter_string);
 	}
 	mutex_unlock(&event_mutex);
-
+out:
 	return err;
 }
 
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