linux-kernel - Re: [PATCH 3/3] checkpatch.pl: Add check for task comm references

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Date:	Mon, 16 May 2011 14:34:14 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Michal Nazarewicz <mina86@...a86.com>
cc:	LKML <linux-kernel@...r.kernel.org>,
	John Stultz <john.stultz@...aro.org>,
	"Ted Ts'o" <tytso@....edu>, Jiri Slaby <jirislaby@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Subject: Re: [PATCH 3/3] checkpatch.pl: Add check for task comm references

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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