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From: David Rientjes <rientjes@google.com>
To: Michal Nazarewicz <mina86@mina86.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	John Stultz <john.stultz@linaro.org>, Ted Ts'o <tytso@mit.edu>,
	Jiri Slaby <jirislaby@gmail.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org
Subject: Re: [PATCH 3/3] checkpatch.pl: Add check for task comm references
Date: Mon, 16 May 2011 14:34:14 -0700 (PDT)	[thread overview]
Message-ID: <alpine.DEB.2.00.1105161431550.4353@chino.kir.corp.google.com> (raw)
In-Reply-To: <op.vvlfaobx3l0zgt@mnazarewicz-glaptop>

On Mon, 16 May 2011, Michal Nazarewicz wrote:

> > Now that accessing current->comm needs to be protected,
> > @@ -2868,6 +2868,10 @@ sub process {
> > 			WARN("usage of NR_CPUS is often wrong - consider using
> > cpu_possible(), num_possible_cpus(), for_each_possible_cpu(), etc\n" .
> > $herecurr);
> > 		}
> > +# check for current->comm usage
> > +		if ($line =~ /\b(?:current|task|tsk|t)\s*->\s*comm\b/) {
> 
> Not a checkpatch.pl expert but as far as I'm concerned, that looks reasonable.
> 
> I was sort of worried that t->comm could produce quite a few false positives
> but all its appearances in the kernel (seem to) refer to task.
> 

It's guaranteed to generate false positives since perf events uses a field 
of the same name to store a thread's comm, so I think the most important 
thing is for the checkpatch output to specify that this _may_ be a 
dereference of a thread's comm that needs get_task_comm() or %ptc.

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  reply	other threads:[~2011-05-16 21:34 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-16 21:19 [PATCH 0/3] v4 Improve task->comm locking situation John Stultz
2011-05-16 21:19 ` [PATCH 1/3] comm: Introduce comm_lock seqlock to protect task->comm access John Stultz
2011-05-16 22:01   ` Jiri Slaby
2011-05-17  1:47     ` John Stultz
2011-05-18  0:28   ` KOSAKI Motohiro
2011-05-16 21:19 ` [PATCH 2/3] printk: Add %ptc to safely print a task's comm John Stultz
2011-05-16 21:54   ` Jiri Slaby
2011-05-16 23:10     ` John Stultz
2011-05-16 23:56       ` Joe Perches
2011-05-17  0:11         ` John Stultz
2011-05-17  7:21         ` Jiri Slaby
2011-05-18  0:32   ` KOSAKI Motohiro
2011-05-16 21:19 ` [PATCH 3/3] checkpatch.pl: Add check for task comm references John Stultz
2011-05-16 21:29   ` Michal Nazarewicz
2011-05-16 21:34     ` David Rientjes [this message]
2011-05-16 23:04       ` Joe Perches
2011-05-16 23:11         ` Michal Nazarewicz
2011-05-16 23:22           ` Joe Perches
2011-05-17 20:47 [PATCH 0/3] v5 Improve task->comm locking situation John Stultz
2011-05-17 20:47 ` [PATCH 3/3] checkpatch.pl: Add check for task comm references John Stultz
2011-05-17 20:58   ` Jiri Slaby
2011-05-17 21:04   ` Michal Nazarewicz

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