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From: Will Deacon <will.deacon@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>,
	Ingo Molnar <mingo@elte.hu>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Paul E.McKenney" <paulmck@linux.vnet.ibm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Waiman Long <waiman.long@hp.com>,
	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>,
	Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>George
	Spelvin <lin>
Subject: Re: [PATCH v7 5/6] MCS Lock: allow architectures to hook in to contended paths
Date: Mon, 20 Jan 2014 14:11:57 +0000	[thread overview]
Message-ID: <20140120141157.GC9868@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <20140120121948.GD31570@twins.programming.kicks-ass.net>

On Mon, Jan 20, 2014 at 12:19:48PM +0000, Peter Zijlstra wrote:
> On Thu, Jan 16, 2014 at 04:08:31PM -0800, Tim Chen wrote:
> > +#ifndef arch_mcs_spin_lock_contended
> > +/*
> > + * Using smp_load_acquire() provides a memory barrier that ensures
> > + * subsequent operations happen after the lock is acquired.
> > + */
> > +#define arch_mcs_spin_lock_contended(l)					\
> > +	while (!(smp_load_acquire(l))) {				\
> > +		arch_mutex_cpu_relax();					\
> > +	}
> > +#endif
> 
> I think that wants to be:
> 
> #define arch_mcs_spin_lock_contended(l)				\
> do {								\
> 	while (!smp_load_acquire(l))				\
> 		arch_mutex_cpu_relax();				\
> } while (0)
> 
> So that we properly eat the ';' in: arch_mcs_spin_lock_contended(l);.

Yeah, that's better.

Tim: are you happy making that change please?

Will

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WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>,
	Ingo Molnar <mingo@elte.hu>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Paul E.McKenney" <paulmck@linux.vnet.ibm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Waiman Long <waiman.long@hp.com>,
	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>,
	Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
	George Spelvin <linux@horizon.com>,
	"H. Peter Anvin" <hpa@zytor.com>, Arnd Bergmann <arnd@arndb.de>,
	Aswin Chandramouleeswaran <aswin@hp.com>,
	Scott J Norton <scott.norton@hp.com>,
	"Figo.zhang" <figo1802@gmail.com>
Subject: Re: [PATCH v7 5/6] MCS Lock: allow architectures to hook in to contended paths
Date: Mon, 20 Jan 2014 14:11:57 +0000	[thread overview]
Message-ID: <20140120141157.GC9868@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <20140120121948.GD31570@twins.programming.kicks-ass.net>

On Mon, Jan 20, 2014 at 12:19:48PM +0000, Peter Zijlstra wrote:
> On Thu, Jan 16, 2014 at 04:08:31PM -0800, Tim Chen wrote:
> > +#ifndef arch_mcs_spin_lock_contended
> > +/*
> > + * Using smp_load_acquire() provides a memory barrier that ensures
> > + * subsequent operations happen after the lock is acquired.
> > + */
> > +#define arch_mcs_spin_lock_contended(l)					\
> > +	while (!(smp_load_acquire(l))) {				\
> > +		arch_mutex_cpu_relax();					\
> > +	}
> > +#endif
> 
> I think that wants to be:
> 
> #define arch_mcs_spin_lock_contended(l)				\
> do {								\
> 	while (!smp_load_acquire(l))				\
> 		arch_mutex_cpu_relax();				\
> } while (0)
> 
> So that we properly eat the ';' in: arch_mcs_spin_lock_contended(l);.

Yeah, that's better.

Tim: are you happy making that change please?

Will

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
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  reply	other threads:[~2014-01-20 14:11 UTC|newest]

Thread overview: 80+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <cover.1389890175.git.tim.c.chen@linux.intel.com>
2014-01-17  0:08 ` [PATCH v7 0/6] MCS Lock: MCS lock code cleanup and optimizations Tim Chen
2014-01-17  0:08   ` Tim Chen
2014-01-20 13:58   ` Peter Zijlstra
2014-01-20 13:58     ` Peter Zijlstra
2014-01-20 13:58     ` Peter Zijlstra
2014-01-20 14:22     ` Ingo Molnar
2014-01-20 14:22       ` Ingo Molnar
2014-01-17  0:08 ` [PATCH v7 1/6] MCS Lock: Restructure the MCS lock defines and locking code into its own file Tim Chen
2014-01-17  0:08   ` Tim Chen
2014-01-20  2:28   ` Paul E. McKenney
2014-01-20  2:28     ` Paul E. McKenney
2014-01-20  2:28     ` Paul E. McKenney
2014-01-20  2:28     ` Paul E. McKenney
2014-01-20 12:07   ` Peter Zijlstra
2014-01-20 12:07     ` Peter Zijlstra
2014-01-20 12:07     ` Peter Zijlstra
2014-01-20 19:31     ` Tim Chen
2014-01-20 19:31       ` Tim Chen
2014-01-20 19:31       ` Tim Chen
2014-01-17  0:08 ` [PATCH v7 2/6] MCS Lock: optimizations and extra comments Tim Chen
2014-01-17  0:08   ` Tim Chen
2014-01-20  2:29   ` Paul E. McKenney
2014-01-20  2:29     ` Paul E. McKenney
2014-01-20  2:29     ` Paul E. McKenney
2014-01-20 13:58   ` Peter Zijlstra
2014-01-20 13:58     ` Peter Zijlstra
2014-01-20 13:58     ` Peter Zijlstra
2014-01-20 19:11     ` Tim Chen
2014-01-20 19:11       ` Tim Chen
2014-01-20 19:11       ` Tim Chen
2014-01-17  0:08 ` [PATCH v7 3/6] MCS Lock: Move mcs_lock/unlock function into its own file Tim Chen
2014-01-17  0:08   ` Tim Chen
2014-01-20  2:32   ` Paul E. McKenney
2014-01-20  2:32     ` Paul E. McKenney
2014-01-20  2:32     ` Paul E. McKenney
2014-01-20 12:15   ` Peter Zijlstra
2014-01-20 12:15     ` Peter Zijlstra
2014-01-20 12:15     ` Peter Zijlstra
2014-01-17  0:08 ` [PATCH v7 4/6] MCS Lock: Barrier corrections Tim Chen
2014-01-17  0:08   ` Tim Chen
2014-01-20  2:33   ` Paul E. McKenney
2014-01-20  2:33     ` Paul E. McKenney
2014-01-20  2:33     ` Paul E. McKenney
2014-01-20  7:09     ` Ingo Molnar
2014-01-20  7:09       ` Ingo Molnar
2014-01-17  0:08 ` [PATCH v7 5/6] MCS Lock: allow architectures to hook in to contended paths Tim Chen
2014-01-17  0:08   ` Tim Chen
2014-01-20  2:34   ` Paul E. McKenney
2014-01-20  2:34     ` Paul E. McKenney
2014-01-20  2:34     ` Paul E. McKenney
2014-01-20 12:19   ` Peter Zijlstra
2014-01-20 12:19     ` Peter Zijlstra
2014-01-20 12:19     ` Peter Zijlstra
2014-01-20 14:11     ` Will Deacon [this message]
2014-01-20 14:11       ` Will Deacon
2014-01-20 16:43       ` Tim Chen
2014-01-20 16:43         ` Tim Chen
2014-01-17  0:08 ` [PATCH v7 6/6] MCS Lock: add Kconfig entries to allow arch-specific hooks Tim Chen
2014-01-17  0:08   ` Tim Chen
2014-01-20  2:35   ` Paul E. McKenney
2014-01-20  2:35     ` Paul E. McKenney
2014-01-20  2:35     ` Paul E. McKenney
2014-01-20 12:30   ` Peter Zijlstra
2014-01-20 12:30     ` Peter Zijlstra
2014-01-20 12:30     ` Peter Zijlstra
2014-01-20 12:35     ` Geert Uytterhoeven
2014-01-20 12:35       ` Geert Uytterhoeven
2014-01-20 12:36       ` Peter Zijlstra
2014-01-20 12:36         ` Peter Zijlstra
2014-01-20 12:38         ` Ingo Molnar
2014-01-20 12:38           ` Ingo Molnar
2014-01-20 13:17     ` Peter Zijlstra
2014-01-20 13:17       ` Peter Zijlstra
2014-01-20 13:17       ` Peter Zijlstra
2014-01-20 23:31     ` Tim Chen
2014-01-20 23:31       ` Tim Chen
2014-01-20 23:31       ` Tim Chen
2014-01-21  9:47       ` Peter Zijlstra
2014-01-21  9:47         ` Peter Zijlstra
2014-01-21  9:47         ` Peter Zijlstra

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