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Subject[for-next][PATCH 6/6] tracing: Fix leak of ring buffer data when new instances creation fails
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

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>
---
kernel/trace/trace.c | 22 ++++++++++++++++++++--
1 file 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);
--
2.0.0.rc2



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