Subject: Re: [PATCH 2/3] printk: Add %ptc to safely print a task's comm
From: John Stultz <john.stultz@linaro.org>
To: Andi Kleen <andi@firstfloor.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
In-Reply-To: <m2sjsli1ft.fsf@firstfloor.org>
References: <1305073386-4810-1-git-send-email-john.stultz@linaro.org>
	 <1305073386-4810-3-git-send-email-john.stultz@linaro.org>
	 <m2sjsli1ft.fsf@firstfloor.org>
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Date: Wed, 11 May 2011 14:04:27 -0700
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On Wed, 2011-05-11 at 10:36 -0700, Andi Kleen wrote:
> 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.

Yea. That's on my queue.

thanks
-john


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