From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758969Ab0KPVI7 (ORCPT ); Tue, 16 Nov 2010 16:08:59 -0500 Received: from claw.goop.org ([74.207.240.146]:50465 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758864Ab0KPVIz (ORCPT ); Tue, 16 Nov 2010 16:08:55 -0500 From: Jeremy Fitzhardinge To: Peter Zijlstra Cc: Linux Kernel Mailing List , Nick Piggin , Mathieu Desnoyers , =?UTF-8?q?Am=C3=A9rico=20Wang?= , Eric Dumazet , Jan Beulich , Avi Kivity , Xen-devel , "H. Peter Anvin" , Linux Virtualization , Srivatsa Vaddagiri , Jeremy Fitzhardinge Subject: [PATCH 06/14] x86/ticketlock: make __ticket_spin_trylock common Date: Tue, 16 Nov 2010 13:08:37 -0800 Message-Id: <731eebc252279f51d331f05f353c5ca03bcd99ca.1289940821.git.jeremy.fitzhardinge@citrix.com> X-Mailer: git-send-email 1.7.2.3 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jeremy Fitzhardinge Make trylock code common regardless of ticket size. Signed-off-by: Jeremy Fitzhardinge --- arch/x86/include/asm/spinlock.h | 49 +++++++-------------------------- arch/x86/include/asm/spinlock_types.h | 6 +++- 2 files changed, 14 insertions(+), 41 deletions(-) diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index f722f96..3afb1a7 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -98,48 +98,19 @@ static __always_inline void __ticket_spin_lock(struct arch_spinlock *lock) out: 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; - - asm volatile("movzwl %2, %0\n\t" - "cmpb %h0,%b0\n\t" - "leal 0x100(%" REG_PTR_MODE "0), %1\n\t" - "jne 1f\n\t" - LOCK_PREFIX "cmpxchgw %w1,%2\n\t" - "1:" - "sete %b1\n\t" - "movzbl %b1,%0\n\t" - : "=&a" (tmp), "=&q" (new), "+m" (lock->slock) - : - : "memory", "cc"); - - return tmp; -} -#else -static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) -{ - unsigned tmp; - unsigned new; - - asm volatile("movl %2,%0\n\t" - "movl %0,%1\n\t" - "roll $16, %0\n\t" - "cmpl %0,%1\n\t" - "leal 0x00010000(%" REG_PTR_MODE "0), %1\n\t" - "jne 1f\n\t" - LOCK_PREFIX "cmpxchgl %1,%2\n\t" - "1:" - "sete %b1\n\t" - "movzbl %b1,%0\n\t" - : "=&a" (tmp), "=&q" (new), "+m" (lock->slock) - : - : "memory", "cc"); - - return tmp; + arch_spinlock_t old, new; + + old.tickets = ACCESS_ONCE(lock->tickets); + if (old.tickets.head != old.tickets.tail) + return 0; + + new.head_tail = old.head_tail + (1 << TICKET_SHIFT); + + /* cmpxchg is a full barrier, so nothing can move before it */ + return cmpxchg(&lock->head_tail, old.head_tail, new.head_tail) == old.head_tail; } -#endif static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock) { diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h index e3ad1e3..72e154e 100644 --- a/arch/x86/include/asm/spinlock_types.h +++ b/arch/x86/include/asm/spinlock_types.h @@ -9,8 +9,10 @@ #if (CONFIG_NR_CPUS < 256) typedef u8 __ticket_t; +typedef u16 __ticketpair_t; #else typedef u16 __ticket_t; +typedef u32 __ticketpair_t; #endif #define TICKET_SHIFT (sizeof(__ticket_t) * 8) @@ -18,14 +20,14 @@ typedef u16 __ticket_t; typedef struct arch_spinlock { union { - unsigned int slock; + __ticketpair_t head_tail; struct __raw_tickets { __ticket_t head, tail; } tickets; }; } arch_spinlock_t; -#define __ARCH_SPIN_LOCK_UNLOCKED { { .slock = 0 } } +#define __ARCH_SPIN_LOCK_UNLOCKED { { 0 } } typedef struct { unsigned int lock; -- 1.7.2.3