Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755462AbaAMQln (ORCPT ); Mon, 13 Jan 2014 11:41:43 -0500 Received: from g6t0187.atlanta.hp.com ([15.193.32.64]:30214 "EHLO g6t0187.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754893AbaAMQlk (ORCPT ); Mon, 13 Jan 2014 11:41:40 -0500 Message-ID: <52D4172E.6030706@hp.com> Date: Mon, 13 Jan 2014 11:41:18 -0500 From: Waiman Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12 MIME-Version: 1.0 To: Peter Zijlstra CC: Daniel J Blueman , "Paul E. McKenney" , Linux Kernel Subject: Re: [PATCH v8 4/4] qrwlock: Use smp_store_release() in write_unlock() References: <52D353C8.4000000@numascale.com> In-Reply-To: <52D353C8.4000000@numascale.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/12/2014 09:47 PM, Daniel J Blueman wrote: > On Thursday, 9 January 2014 01:10:03 UTC+8, Waiman Long wrote: > > This patch modifies the queue_write_unlock() function to use the > > new smp_store_release() function in another pending patch. It also > > removes the temporary implementation of smp_load_acquire() and > > smp_store_release() function in qrwlock.c. > > > > This patch should only be merged if PeterZ's linux-arch patch patch > > was merged. > > > > Signed-off-by: Waiman Long > > Reviewed-by: Paul E. McKenney > > --- > > include/asm-generic/qrwlock.h | 4 +--- > > kernel/locking/qrwlock.c | 34 > ---------------------------------- > > 2 files changed, 1 insertions(+), 37 deletions(-) > > > > diff --git a/include/asm-generic/qrwlock.h > b/include/asm-generic/qrwlock.h > > index 2b9a7b4..4d4bd04 100644 > > --- a/include/asm-generic/qrwlock.h > > +++ b/include/asm-generic/qrwlock.h > > @@ -179,9 +179,7 @@ static inline void queue_write_unlock(struct > qrwlock *lock) > > /* > > * Make sure that none of the critical section will be leaked out. > > */ > > - smp_mb__before_clear_bit(); > > - ACCESS_ONCE(lock->cnts.writer) = 0; > > - smp_mb__after_clear_bit(); > > + smp_store_release(&lock->cnts.writer, 0) > > This will fail compilation, so probably needs further testing with > Peter's load_acquire/store_release barrier patches. > Peter, I found out that the build failure was caused by the fact that the __native_word() macro (used internally by compiletime_assert_atomic()) allows only a size of 4 or 8 for x86-64. The data type that I used is a byte. Is there a reason why byte and short are not considered native? -Longman -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/