From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755403Ab0KCPNp (ORCPT ); Wed, 3 Nov 2010 11:13:45 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:44993 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753532Ab0KCPNo (ORCPT ); Wed, 3 Nov 2010 11:13:44 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=VOOdcVD4+0thgk9udZyXhE97ZqtAXGRKZNBGI+ON8r2Palp3q2nFq2Utqe9jaT+KKI mQFrTwJ6Af940SiB+SBBJzPLC2p0CWz8uVMJb8/f6zVf4Iux2cIGc1VLkQD4lsEcKCCy BdTK81KeLiyVK3axKLDgxgP+KVTD21Kg6+pIM= Subject: Re: [PATCH 03/20] x86/ticketlock: Use C for __ticket_spin_unlock From: Eric Dumazet To: Jeremy Fitzhardinge Cc: Peter Zijlstra , Linux Kernel Mailing List , Nick Piggin , Jan Beulich , Avi Kivity , Xen-devel , "H. Peter Anvin" , Linux Virtualization , Srivatsa Vaddagiri , Jeremy Fitzhardinge In-Reply-To: <20092775a9df07a5a75820ac250194b535279d51.1288794124.git.jeremy.fitzhardinge@citrix.com> References: <20092775a9df07a5a75820ac250194b535279d51.1288794124.git.jeremy.fitzhardinge@citrix.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 03 Nov 2010 16:13:38 +0100 Message-ID: <1288797218.2511.143.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le mercredi 03 novembre 2010 à 10:59 -0400, Jeremy Fitzhardinge a écrit : > From: Jeremy Fitzhardinge > > If we don't need to use a locked inc for unlock, then implement it in C. > > Signed-off-by: Jeremy Fitzhardinge > --- > arch/x86/include/asm/spinlock.h | 33 ++++++++++++++++++--------------- > 1 files changed, 18 insertions(+), 15 deletions(-) > > diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h > index 6711d36..082990a 100644 > --- a/arch/x86/include/asm/spinlock.h > +++ b/arch/x86/include/asm/spinlock.h > @@ -33,9 +33,23 @@ > * On PPro SMP or if we are using OOSTORE, we use a locked operation to unlock > * (PPro errata 66, 92) > */ > -# define UNLOCK_LOCK_PREFIX LOCK_PREFIX > +static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock) > +{ > + if (sizeof(lock->tickets.head) == sizeof(u8)) > + asm (LOCK_PREFIX "incb %0" > + : "+m" (lock->tickets.head) : : "memory"); > + else > + asm (LOCK_PREFIX "incw %0" > + : "+m" (lock->tickets.head) : : "memory"); > + > +} > #else > -# define UNLOCK_LOCK_PREFIX > +static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock) > +{ > + barrier(); technically speaking, it should be : smp_wmb() > + lock->tickets.head++; > + barrier(); Not sure you need this one. > +} > #endif >