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Subject: Re: [PATCH v6 5/6] MCS Lock: Restructure the MCS lock defines and
 locking code into its own file
From: Joe Perches <joe@perches.com>
Date: Fri, 27 Sep 2013 06:44:55 -0700
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To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>, Tim Chen <tim.c.chen@linux.intel.com>, Jason Low <jason.low2@hp.com>, Davidlohr Bueso <davidlohr@hp.com>, Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>, Andrea Arcangeli <aarcange@redhat.com>, Alex Shi <alex.shi@linaro.org>, Andi Kleen <andi@firstfloor.org>, Michel Lespinasse <walken@google.com>, Davidlohr Bueso <davidlohr.bueso@hp.com>, Matthew R Wilcox <matthew.r.wilcox@intel.com>, Dave Hansen <dave.hansen@intel.com>, Rik van Riel <riel@redhat.com>, Peter Hurley <peter@hurleysoftware.com>, linux-kernel@vger.kernel.org, linux-mm <linux-mm@kvack.org>

On Fri, 2013-09-27 at 13:23 +0200, Peter Zijlstra wrote:
> checkpatch.pl should really warn about that; and it appears there
> code in there for that; however:
> 
> # grep -C3 smp_mb scripts/checkpatch.pl 
[]
> # check for memory barriers without a comment.
>                 if ($line =~ /\b(mb|rmb|wmb|read_barrier_depends|smp_mb|smp_rmb|smp_wmb|smp_read_barrier_depends)\(/) {
>                         if (!ctx_has_comment($first_line, $linenr)) {
>                                 CHK("MEMORY_BARRIER",
>                                     "memory barrier without comment\n" . $herecurr);
[]
> # scripts/checkpatch.pl -f kernel/mutex.c 2>&1 | grep memory
> #
> 
> so that appears to be completely broken :/
> 
> Joe, any clue what's up with that?

It's a CHK test, so it's only tested with --strict

$ scripts/checkpatch.pl -f --strict kernel/mutex.c 2>&1 | grep memory
CHECK: memory barrier without comment
CHECK: memory barrier without comment

It could be changed to WARN so it's always on.


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