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

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Date:	Tue, 17 May 2011 22:58:21 +0200
From:	Jiri Slaby <jirislaby@...il.com>
To:	John Stultz <john.stultz@...aro.org>
CC:	LKML <linux-kernel@...r.kernel.org>, Joe Perches <joe@...ches.com>,
	Michal Nazarewicz <mina86@...a86.com>,
	Andy Whitcroft <apw@...onical.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	David Rientjes <rientjes@...gle.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 05/17/2011 10:47 PM, John Stultz wrote:
> Now that accessing current->comm needs to be protected,
> avoid new current->comm or other task->comm usage by adding
> a warning to checkpatch.pl.
> 
> Fair warning: I know zero perl, so this was written in the
> style of "monkey see, monkey do". It does appear to work
> in my testing though.
> 
> Thanks to Jiri Slaby, Michal Nazarewicz and Joe Perches
> for help improving the regex!
> 
> Close review and feedback would be appreciated.
> 
> CC: Joe Perches <joe@...ches.com>
> CC: Michal Nazarewicz <mina86@...a86.com>
> CC: Andy Whitcroft <apw@...onical.com>
> CC: Jiri Slaby <jirislaby@...il.com>
> CC: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> CC: David Rientjes <rientjes@...gle.com>
> CC: Dave Hansen <dave@...ux.vnet.ibm.com>
> CC: Andrew Morton <akpm@...ux-foundation.org>
> CC: linux-mm@...ck.org
> Signed-off-by: John Stultz <john.stultz@...aro.org>
> ---
>  scripts/checkpatch.pl |    7 +++++++
>  1 files changed, 7 insertions(+), 0 deletions(-)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index d867081..a67ea69 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -2868,6 +2868,13 @@ 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
> +		our $common_comm_vars = qr{(?x:
> +		        current|tsk|p|task|curr|chip|t|object|me

Hrm, chip->comm looks like a total bullshit.
object->comm refers to kmemleak object, so this would trigger false
alarms too.

> +		)};
> +		if ($line =~ /\b($common_comm_vars)\s*->\s*comm\b/) {
> +			WARN("comm access needs to be protected. Use get_task_comm, or printk's \%ptc formatting.\n" . $herecurr);
> +		}
>  # check for %L{u,d,i} in strings
>  		my $string;
>  		while ($line =~ /(?:^|")([X\t]*)(?:"|$)/g) {

thanks,
-- 
js
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