From 5554720482a631702146a959db22fe417740e0a6 Mon Sep 17 00:00:00 2001
From: Li Zefan <lizf@cn.fujitsu.com>
Date: Wed, 25 Mar 2009 17:21:26 +0800
Subject: [PATCH] blktrace: fix the original blktrace

Currently the original blktrace, which is using relay and is used via
ioctl, is broken. You can use ftrace to see the output of blktrace,
but user-space blktrace is unusable.

It's broken by "blktrace: add ftrace plugin"
(c71a896154119f4ca9e89d6078f5f63ad60ef199)

 -	if (unlikely(bt->trace_state != Blktrace_running))
 +	if (unlikely(bt->trace_state != Blktrace_running || !blk_tracer_enabled))
		return;

With this patch, both ioctl and ftrace can be used, but of course you
can't use both of them at the same time.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
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