[tip:perf/core] tracing: Check return value of tracing_dentry_percpu()

[tip-bot for Namhyung Kim <namhyung.kim@lge.com>]

Commit-ID:  0a3d7ce7e6caa8c39cb5184bd9047a01a40abc2a
Gitweb:     http://git.kernel.org/tip/0a3d7ce7e6caa8c39cb5184bd9047a01a40abc2a
Author:     Namhyung Kim <namhyung.kim@lge.com>
AuthorDate: Mon, 23 Apr 2012 10:11:57 +0900
Committer:  Steven Rostedt <rostedt@goodmis.org>
CommitDate: Wed, 16 May 2012 19:50:37 -0400

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>
---
 kernel/trace/trace.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dfbd86c..0ed4df0 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) {