From: Andi Kleen <andi@firstfloor.org>
To: John Stultz <john.stultz@linaro.org>
Cc: LKML <linux-kernel@vger.kernel.org>, "Ted Ts'o" <tytso@mit.edu>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        David Rientjes <rientjes@google.com>,
        Dave Hansen <dave@linux.vnet.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org
Subject: Re: [PATCH 2/3] printk: Add %ptc to safely print a task's comm
References: <1305073386-4810-1-git-send-email-john.stultz@linaro.org>
	<1305073386-4810-3-git-send-email-john.stultz@linaro.org>
Date: Wed, 11 May 2011 10:36:54 -0700
In-Reply-To: <1305073386-4810-3-git-send-email-john.stultz@linaro.org> (John
	Stultz's message of "Tue, 10 May 2011 17:23:05 -0700")
Message-ID: <m2sjsli1ft.fsf@firstfloor.org>
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John Stultz <john.stultz@linaro.org> writes:

> Acessing task->comm requires proper locking. However in the past
> access to current->comm could be done without locking. This
> is no longer the case, so all comm access needs to be done
> while holding the comm_lock.
>
> In my attempt to clean up unprotected comm access, I've noticed
> most comm access is done for printk output. To simpify correct
> locking in these cases, I've introduced a new %ptc format,
> which will safely print the corresponding task's comm.
>
> Example use:
> printk("%ptc: unaligned epc - sending SIGBUS.\n", current);

Neat. But you probably want a checkpatch rule for this too
to catch new offenders.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only
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