tracing: Fix leak of ring buffer data when new instances creation fails

Yoshihiro Yunomae reported that the ring buffer data for a trace
instance does not get properly cleaned up when it fails. He proposed
a patch that manually cleaned the data up and addad a bunch of labels.
The labels are not needed because all trace array is allocated with
a kzalloc which initializes it to 0 and all kfree()s can take a NULL
pointer and will ignore it.

Adding a new helper function free_trace_buffers() that can also take
null buffers to free the buffers that were allocated by
allocate_trace_buffers().

Link: http://lkml.kernel.org/r/20140605223522.32311.31664.stgit@yunodevel

Reported-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 20 insertions, 2 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e29edee1542a..26cfff38e2ab 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6232,6 +6232,25 @@ static int allocate_trace_buffers(struct trace_array *tr, int size)
         return 0;
 }
 
+static void free_trace_buffers(struct trace_array *tr)
+{
+        if (!tr)
+                return;
+
+        if (tr->trace_buffer.buffer) {
+                ring_buffer_free(tr->trace_buffer.buffer);
+                tr->trace_buffer.buffer = NULL;
+                free_percpu(tr->trace_buffer.data);
+        }
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+        if (tr->max_buffer.buffer) {
+                ring_buffer_free(tr->max_buffer.buffer);
+                tr->max_buffer.buffer = NULL;
+        }
+#endif
+}
+
 static int new_instance_create(const char *name)
 {
         struct trace_array *tr;
@@ -6290,8 +6309,7 @@ static int new_instance_create(const char *name)
         return 0;
 
  out_free_tr:
-        if (tr->trace_buffer.buffer)
-                ring_buffer_free(tr->trace_buffer.buffer);
+        free_trace_buffers(tr);
         free_cpumask_var(tr->tracing_cpumask);
         kfree(tr->name);
         kfree(tr);