[PATCH] tracing: fix a potential mutex deadlock in register_tracer

[Chunyu Hu]

commit d39cdd2036a63eef17a14efbd969405ca5612886 ("tracing: Make
tracer_flags use the right set_flag callback")  introduces a potential
mutex deadlock issue, as it forgets to free the mutex when allocaing
the tracer_flags gets fail. This patch fix the issue. The issue was
found by Dan Carpenter through Smatch static code check tool.

Signed-off-by: Chunyu Hu <ch...@redhat.com>
---
 kernel/trace/trace.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b401a18..0ae4604 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1256,8 +1256,10 @@ int __init register_tracer(struct tracer *type)
        if (!type->flags) {
                /*allocate a dummy tracer_flags*/
                type->flags = kmalloc(sizeof(*type->flags), GFP_KERNEL);
-               if (!type->flags)
-                       return -ENOMEM;
+               if (!type->flags) {
+                       ret = -ENOMEM;
+                       goto out;
+               }
                type->flags->val = 0;
                type->flags->opts = dummy_tracer_opt;
        } else
-- 
1.8.3.1