From: Peter Zijlstra <peterz@infradead.org>
To: Joe Perches <joe@perches.com>
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>
Subject: Re: [PATCH v6 5/6] MCS Lock: Restructure the MCS lock defines and locking code into its own file
Date: Fri, 27 Sep 2013 16:18:45 +0200 [thread overview]
Message-ID: <20130927141845.GB15690@laptop.programming.kicks-ass.net> (raw)
In-Reply-To: <1380290700.17366.95.camel@joe-AO722>
On Fri, Sep 27, 2013 at 07:05:00AM -0700, Joe Perches wrote:
> On Fri, 2013-09-27 at 15:48 +0200, Peter Zijlstra wrote:
> > On Fri, Sep 27, 2013 at 06:44:55AM -0700, Joe Perches wrote:
> > > 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.
> >
> > Yes please, we can't be too careful with memory barriers.
>
> I'll send the patch separately.
>
> It seems a pretty noisy test.
> There are 13 hits just in arch/x86/kernel/
Urgh. that wants fixing. We really need to stop getting more and that's
where checkpatch is good at.
At very very bare minimum the comment should mention where the pairing
barrier is; but ideally it should describe the actual ordering.
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next prev parent reply other threads:[~2013-09-27 14:19 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1380144003.git.tim.c.chen@linux.intel.com>
2013-09-25 22:10 ` [PATCH v6 0/6] rwsem: performance optimizations Tim Chen
2013-09-25 22:10 ` [PATCH v6 1/6] rwsem: check the lock before cpmxchg in down_write_trylock Tim Chen
2013-09-25 22:10 ` [PATCH v6 2/6] rwsem: remove 'out' label in do_wake Tim Chen
2013-09-25 22:10 ` [PATCH v6 3/6] rwsem: remove try_reader_grant label do_wake Tim Chen
2013-09-25 22:10 ` [PATCH v6 4/6] rwsem/wake: check lock before do atomic update Tim Chen
2013-09-25 22:10 ` [PATCH v6 5/6] MCS Lock: Restructure the MCS lock defines and locking code into its own file Tim Chen
2013-09-26 6:46 ` Ingo Molnar
2013-09-26 8:40 ` Peter Zijlstra
2013-09-26 9:37 ` Ingo Molnar
2013-09-26 18:18 ` Tim Chen
2013-09-26 19:27 ` Jason Low
2013-09-26 20:06 ` Davidlohr Bueso
2013-09-26 20:23 ` Jason Low
2013-09-26 20:40 ` Davidlohr Bueso
2013-09-26 21:09 ` Jason Low
2013-09-26 21:41 ` Tim Chen
2013-09-26 22:42 ` Jason Low
2013-09-26 22:57 ` Tim Chen
2013-09-27 6:02 ` Ingo Molnar
2013-09-27 6:26 ` Jason Low
2013-09-27 11:23 ` Peter Zijlstra
2013-09-27 13:44 ` Joe Perches
2013-09-27 13:48 ` Peter Zijlstra
2013-09-27 14:05 ` Joe Perches
2013-09-27 14:18 ` Peter Zijlstra [this message]
2013-09-27 14:14 ` [PATCH] checkpatch: Make the memory barrier test noisier Joe Perches
2013-09-27 14:26 ` Peter Zijlstra
2013-09-27 14:34 ` Joe Perches
2013-09-27 14:50 ` Peter Zijlstra
2013-09-27 15:17 ` Paul E. McKenney
2013-09-27 15:34 ` Peter Zijlstra
2013-09-27 16:04 ` Paul E. McKenney
2013-09-27 23:40 ` Oliver Neukum
2013-09-28 7:54 ` Peter Zijlstra
2013-09-27 16:12 ` [PATCH v6 5/6] MCS Lock: Restructure the MCS lock defines and locking code into its own file Jason Low
2013-09-27 16:19 ` Tim Chen
2013-10-02 19:19 ` Waiman Long
2013-10-02 19:30 ` Jason Low
2013-10-02 19:37 ` Waiman Long
2013-09-26 22:22 ` Davidlohr Bueso
2013-09-27 15:29 ` Paul E. McKenney
2013-09-27 18:09 ` Tim Chen
2013-09-28 2:58 ` Waiman Long
2013-09-27 19:38 ` Tim Chen
2013-09-27 20:16 ` Jason Low
2013-09-27 20:38 ` Paul E. McKenney
2013-09-27 22:46 ` Tim Chen
2013-09-27 23:01 ` Paul E. McKenney
2013-09-27 23:54 ` Jason Low
2013-09-28 0:02 ` Davidlohr Bueso
2013-09-28 2:19 ` Paul E. McKenney
2013-09-28 4:34 ` Jason Low
2013-09-30 15:51 ` Waiman Long
2013-09-30 16:10 ` Jason Low
2013-09-30 16:36 ` Waiman Long
2013-10-01 16:48 ` Tim Chen
2013-10-01 20:01 ` Waiman Long
2013-10-01 21:16 ` Tim Chen
2013-10-02 1:25 ` Waiman Long
2013-10-02 18:43 ` Tim Chen
2013-10-02 19:32 ` Waiman Long
2013-09-30 16:28 ` Tim Chen
2013-09-25 22:10 ` [PATCH v6 6/6] rwsem: do optimistic spinning for writer lock acquisition Tim Chen
2013-09-26 6:53 ` Ingo Molnar
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