tracing: Check return value of tracing_dentry_percpu()

If tracing_dentry_percpu() failed, tracing_init_debugfs_percpu()
will try to create each cpu directories on debugfs' root directory
as d_percpu is NULL.

Link: http://lkml.kernel.org/r/1335143517-2285-1-git-send-email-namhyung.kim@lge.com

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Namhyung Kim <namhyung.kim@lge.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dfbd86cc4876..0ed4df0c6a39 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4474,6 +4474,9 @@ static void tracing_init_debugfs_percpu(long cpu)
         struct dentry *d_cpu;
         char cpu_dir[30]; /* 30 characters should be more than enough */
 
+        if (!d_percpu)
+                return;
+
         snprintf(cpu_dir, 30, "cpu%ld", cpu);
         d_cpu = debugfs_create_dir(cpu_dir, d_percpu);
         if (!d_cpu) {