linux-kernel - [PATCH] tracing: Kill the unbalanced tr->ref++ in tracing_buffers

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Message-ID: <20130719153644.GA18899@redhat.com>
Date:	Fri, 19 Jul 2013 17:36:44 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] tracing: Kill the unbalanced tr->ref++ in
	tracing_buffers_open()

tracing_buffers_open() does trace_array_get() and then it wrongly
inrcements tr->ref again under trace_types_lock. This means that
every caller leaks trace_array:

	# cd /sys/kernel/debug/tracing/
	# mkdir instances/X
	# true < instances/X/per_cpu/cpu0/trace_pipe_raw
	# rmdir instances/X
	rmdir: failed to remove `instances/X': Device or resource busy

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/trace/trace.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ee471fb..278c5f5 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4944,8 +4944,6 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp)
 
 	mutex_lock(&trace_types_lock);
 
-	tr->ref++;
-
 	info->iter.tr		= tr;
 	info->iter.cpu_file	= tc->cpu;
 	info->iter.trace	= tr->current_trace;
-- 
1.5.5.1


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