tracing/filters: Defer pred allocation, fix memory leak

The predicates of an event and their filter structure are allocated
when we create an event filter for the first time.

These objects must be created once but each time we come with a new
filter, we overwrite such pre-existing allocation, if any.

Thus, this patch checks if the filter has already been allocated
before going ahead.

Spotted-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
LKML-Reference: <4A9CB1BA.3060402@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index c6b2edfb7fe9ce0dece40197e1f98a2903920c5e..93660fbbf6297dff7894453c32d1942e1840d286 100644 (file)
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -409,6 +409,9 @@ static int init_preds(struct ftrace_event_call *call)
        struct filter_pred *pred;
        int i;
 
+       if (call->filter)
+               return 0;
+
        filter = call->filter = kzalloc(sizeof(*filter), GFP_KERNEL);
        if (!call->filter)
                return -ENOMEM;
@@ -447,11 +450,9 @@ static int init_subsystem_preds(struct event_subsystem *system)
                if (strcmp(call->system, system->name) != 0)
                        continue;
 
-               if (!call->filter) {
-                       err = init_preds(call);
-                       if (err)
-                               return err;
-               }
+               err = init_preds(call);
+               if (err)
+                       return err;
        }
 
        return 0;