From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753065Ab1H3F0z (ORCPT ); Tue, 30 Aug 2011 01:26:55 -0400 Received: from hera.kernel.org ([140.211.167.34]:49010 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751801Ab1H3F0x (ORCPT ); Tue, 30 Aug 2011 01:26:53 -0400 Date: Tue, 30 Aug 2011 05:26:23 GMT From: tip-bot for Jeremy Fitzhardinge Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, hpa@linux.intel.com, jeremy.fitzhardinge@citrix.com Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, hpa@linux.intel.com, jeremy.fitzhardinge@citrix.com In-Reply-To: <4E5BCC40.3030501@goop.org> References: <4E5BCC40.3030501@goop.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/spinlocks] x86, ticketlock: Convert __ticket_spin_lock to use xadd() Git-Commit-ID: 2994488fe5bb721de1ded53af1a2fc41f47f6ddc X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (hera.kernel.org [127.0.0.1]); Tue, 30 Aug 2011 05:26:44 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 2994488fe5bb721de1ded53af1a2fc41f47f6ddc Gitweb: http://git.kernel.org/tip/2994488fe5bb721de1ded53af1a2fc41f47f6ddc Author: Jeremy Fitzhardinge AuthorDate: Tue, 13 Jul 2010 14:07:45 -0700 Committer: H. Peter Anvin CommitDate: Mon, 29 Aug 2011 13:46:07 -0700 x86, ticketlock: Convert __ticket_spin_lock to use xadd() Convert the two variants of __ticket_spin_lock() to use xadd(), which has the effect of making them identical, so remove the duplicate function. Signed-off-by: Jeremy Fitzhardinge Link: http://lkml.kernel.org/r/4E5BCC40.3030501@goop.org Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/spinlock.h | 35 +++++------------------------------ 1 files changed, 5 insertions(+), 30 deletions(-) diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index 5240cde..b69e0b4 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -54,26 +54,22 @@ * save some instructions and make the code more elegant. There really isn't * much between them in performance though, especially as locks are out of line. */ -#if (NR_CPUS < 256) static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) { - register union { - struct __raw_tickets tickets; - unsigned short slock; - } inc = { .slock = 1 << TICKET_SHIFT }; + register struct __raw_tickets inc = { .tail = 1 }; - asm volatile (LOCK_PREFIX "xaddw %w0, %1\n" - : "+Q" (inc), "+m" (lock->slock) : : "memory", "cc"); + inc = xadd(&lock->tickets, inc); for (;;) { - if (inc.tickets.head == inc.tickets.tail) + if (inc.head == inc.tail) break; cpu_relax(); - inc.tickets.head = ACCESS_ONCE(lock->tickets.head); + inc.head = ACCESS_ONCE(lock->tickets.head); } barrier(); /* make sure nothing creeps before the lock is taken */ } +#if (NR_CPUS < 256) static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) { unsigned int tmp, new; @@ -101,27 +97,6 @@ static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) : "memory", "cc"); } #else -static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) -{ - unsigned inc = 1 << TICKET_SHIFT; - __ticket_t tmp; - - asm volatile(LOCK_PREFIX "xaddl %0, %1\n\t" - : "+r" (inc), "+m" (lock->slock) - : : "memory", "cc"); - - tmp = inc; - inc >>= TICKET_SHIFT; - - for (;;) { - if ((__ticket_t)inc == tmp) - break; - cpu_relax(); - tmp = ACCESS_ONCE(lock->tickets.head); - } - barrier(); /* make sure nothing creeps before the lock is taken */ -} - static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) { unsigned tmp;