Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966273Ab0GQBEy (ORCPT ); Fri, 16 Jul 2010 21:04:54 -0400 Received: from claw.goop.org ([74.207.240.146]:46946 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759571Ab0GQBDH (ORCPT ); Fri, 16 Jul 2010 21:03:07 -0400 Message-Id: In-Reply-To: References: Subject: [PATCH RFC 06/12] x86/ticketlock: make __ticket_spin_trylock 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: 3032 Lines: 109 Make trylock code common regardless of ticket size. Signed-off-by: Jeremy Fitzhardinge --- arch/x86/include/asm/spinlock.h | 55 +++++++++----------------------- arch/x86/include/asm/spinlock_types.h | 3 ++ 2 files changed, 19 insertions(+), 39 deletions(-) diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index 4f9fa24..507f83c 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -100,48 +100,25 @@ static __always_inline void __ticket_spin_lock(struct arch_spinlock *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; - - 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; + union { + struct __raw_tickets tickets; + __ticketpair_t slock; + } tmp, new; + int ret; + + tmp.tickets = ACCESS_ONCE(lock->tickets); + if (tmp.tickets.head != tmp.tickets.tail) + return 0; + + new.slock = tmp.slock + (1 << TICKET_SHIFT); + + ret = cmpxchg(&lock->ticketpair, tmp.slock, new.slock) == tmp.slock; + barrier(); /* just make nothing creeps before lock is claimed */ + + return ret; } -#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 4582640..48dafc3 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) @@ -19,6 +21,7 @@ typedef u16 __ticket_t; typedef struct arch_spinlock { union { unsigned int slock; + __ticketpair_t ticketpair; struct __raw_tickets { __ticket_t head, tail; } tickets; -- 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/