Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759617Ab0GQBE6 (ORCPT ); Fri, 16 Jul 2010 21:04:58 -0400 Received: from claw.goop.org ([74.207.240.146]:46941 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759565Ab0GQBDG (ORCPT ); Fri, 16 Jul 2010 21:03:06 -0400 Message-Id: <149c92c8349ee245cb0a6b1d7f306445a019befc.1279328276.git.jeremy.fitzhardinge@citrix.com> In-Reply-To: References: Subject: [PATCH RFC 05/12] x86/ticketlock: make __ticket_spin_lock common To: Linux Kernel Mailing List Cc: Nick Piggin , Peter Zijlstra , Jan Beulich , Avi Kivity , Xen-devel From: Jeremy Fitzhardinge Date: Fri, 16 Jul 2010 18:03:04 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2933 Lines: 86 Aside from the particular form of the xadd instruction, they're identical. So factor out the xadd and use common code for the rest. Signed-off-by: Jeremy Fitzhardinge --- arch/x86/include/asm/spinlock.h | 42 ++++++++++++++++++-------------------- 1 files changed, 20 insertions(+), 22 deletions(-) diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index 7586d7a..4f9fa24 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -69,13 +69,27 @@ static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock) * 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) +static __always_inline struct __raw_tickets __ticket_spin_claim(struct arch_spinlock *lock) { - register struct __raw_tickets inc = { .tail = 1 }; + register struct __raw_tickets tickets = { .tail = 1 }; + + if (sizeof(lock->tickets.head) == sizeof(u8)) + asm volatile (LOCK_PREFIX "xaddw %w0, %1\n" + : "+r" (tickets), "+m" (lock->tickets) + : : "memory", "cc"); + else + asm volatile (LOCK_PREFIX "xaddl %0, %1\n" + : "+r" (tickets), "+m" (lock->tickets) + : : "memory", "cc"); - asm volatile (LOCK_PREFIX "xaddw %w0, %1\n" - : "+r" (inc), "+m" (lock->tickets) : : "memory", "cc"); + return tickets; +} + +static __always_inline void __ticket_spin_lock(struct arch_spinlock *lock) +{ + register struct __raw_tickets inc; + + inc = __ticket_spin_claim(lock); for (;;) { if (inc.head == inc.tail) @@ -86,6 +100,7 @@ static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) 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; @@ -105,23 +120,6 @@ static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) return tmp; } #else -static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) -{ - register struct __raw_tickets inc = { .tickets.tail = 1 }; - - asm volatile(LOCK_PREFIX "xaddl %0, %1\n\t" - : "+r" (inc), "+m" (lock->tickets) - : : "memory", "cc"); - - for (;;) { - if (inc.head == inc.tail) - return; - cpu_relax(); - inc.head = 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; -- 1.7.1.1 -- 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/