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Message-ID: <1399332831.27516.6.camel@joe-AO725>
Subject: Re: [PATCH] printk: Remove separate printk_sched buffers and use
 printk buf instead
From: Joe Perches <joe@perches.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Frederic Weisbecker <fweisbec@gmail.com>, pmladek@suse.cz,
        Jan Kara <jack@suse.cz>, Peter Zijlstra <peterz@infradead.org>,
        John Stultz <john.stultz@linaro.org>,
        Paul Gortmaker <paul.gortmaker@windriver.com>
Date: Mon, 05 May 2014 16:33:51 -0700
In-Reply-To: <20140505191846.35aa6f9b@gandalf.local.home>
References: <20140505191846.35aa6f9b@gandalf.local.home>
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On Mon, 2014-05-05 at 19:18 -0400, Steven Rostedt wrote:
> To prevent deadlocks with doing a printk inside the scheduler,
> printk_sched() was created. The issue is that printk has a console_sem
> that it can grab and release. The release does a wake up if there's a
> task pending on the sem, and this wake up grabs the rq locks that is
> held in the scheduler. This leads to a possible deadlock if the wake up
> uses the same rq as the one with the rq lock held already.
[]
>  kernel/printk/printk.c |   87 +++++++++++++++++++++++++++++++------------------
[]
> @@ -2440,18 +2470,20 @@
>  #define PRINTK_BUF_SIZE		512

Wouldn't this define be unused and shouldn't it be deleted too?