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Subject[095/104] trace_events_filter: Use rcu_assign_pointer() when setting ftrace_event_call->filter
3.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tejun Heo <tj@kernel.org>

commit d3d9acf646679c1981032b0985b386d12fccc60c upstream.

ftrace_event_call->filter is sched RCU protected but didn't use
rcu_assign_pointer(). Use it.

TODO: Add proper __rcu annotation to call->filter and all its users.

-v2: Use RCU_INIT_POINTER() for %NULL clearing as suggested by Eric.

Link: http://lkml.kernel.org/r/20111123164949.GA29639@google.com

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
kernel/trace/trace_events_filter.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1766,7 +1766,7 @@ static int replace_system_preds(struct e
* replace the filter for the call.
*/
filter = call->filter;
- call->filter = filter_item->filter;
+ rcu_assign_pointer(call->filter, filter_item->filter);
filter_item->filter = filter;

fail = false;
@@ -1821,7 +1821,7 @@ int apply_event_filter(struct ftrace_eve
filter = call->filter;
if (!filter)
goto out_unlock;
- call->filter = NULL;
+ RCU_INIT_POINTER(call->filter, NULL);
/* Make sure the filter is not being used */
synchronize_sched();
__free_filter(filter);
@@ -1862,7 +1862,7 @@ out:
* string
*/
tmp = call->filter;
- call->filter = filter;
+ rcu_assign_pointer(call->filter, filter);
if (tmp) {
/* Make sure the call is done with the filter */
synchronize_sched();



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