trace_events_filter: Use rcu_assign_pointer() when setting ftrace_event_call->filter

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>
Cc: stable@kernel.org # (2.6.39+)
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 816d3d074979306713836d9447382cb641aecb54..d6e7926dcd268228716abcd3bd91633344bd8608 100644 (file)
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1686,7 +1686,7 @@ static int replace_system_preds(struct event_subsystem *system,
                 * 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;
@@ -1741,7 +1741,7 @@ int apply_event_filter(struct ftrace_event_call *call, char *filter_string)
                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);
@@ -1782,7 +1782,7 @@ 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();