Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757205AbaAHRAk (ORCPT ); Wed, 8 Jan 2014 12:00:40 -0500 Received: from g1t0029.austin.hp.com ([15.216.28.36]:9258 "EHLO g1t0029.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756963AbaAHRAd (ORCPT ); Wed, 8 Jan 2014 12:00:33 -0500 From: Waiman Long To: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Arnd Bergmann Cc: linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Steven Rostedt , Andrew Morton , Michel Lespinasse , Andi Kleen , Rik van Riel , "Paul E. McKenney" , Linus Torvalds , Raghavendra K T , George Spelvin , Tim Chen , "Aswin Chandramouleeswaran\"" , Scott J Norton , Waiman Long Subject: [PATCH v8 2/4] qrwlock x86: Enable x86 to use queue read/write lock Date: Wed, 8 Jan 2014 11:59:34 -0500 Message-Id: <1389200376-62792-3-git-send-email-Waiman.Long@hp.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1389200376-62792-1-git-send-email-Waiman.Long@hp.com> References: <1389200376-62792-1-git-send-email-Waiman.Long@hp.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch makes the necessary changes at the x86 architecture specific layer to enable the presence of the CONFIG_QUEUE_RWLOCK kernel option to replace the read/write lock by the queue read/write lock. It also enables the CONFIG_QUEUE_RWLOCK option by default for x86 which will force the use of queue read/write lock. That will greatly improve the fairness of read/write lock and eliminate live-lock situation where one task may not get the lock for an indefinite period of time. Signed-off-by: Waiman Long Reviewed-by: Paul E. McKenney --- arch/x86/Kconfig | 1 + arch/x86/include/asm/spinlock.h | 2 ++ arch/x86/include/asm/spinlock_types.h | 4 ++++ 3 files changed, 7 insertions(+), 0 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index e903c71..c4a9c54 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -124,6 +124,7 @@ config X86 select RTC_LIB select HAVE_DEBUG_STACKOVERFLOW select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64 + select QUEUE_RWLOCK config INSTRUCTION_DECODER def_bool y diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index bf156de..8fb88c5 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -188,6 +188,7 @@ static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) cpu_relax(); } +#ifndef CONFIG_QUEUE_RWLOCK /* * Read-write spinlocks, allowing multiple readers * but only one writer. @@ -270,6 +271,7 @@ static inline void arch_write_unlock(arch_rwlock_t *rw) asm volatile(LOCK_PREFIX WRITE_LOCK_ADD(%1) "%0" : "+m" (rw->write) : "i" (RW_LOCK_BIAS) : "memory"); } +#endif /* CONFIG_QUEUE_RWLOCK */ #define arch_read_lock_flags(lock, flags) arch_read_lock(lock) #define arch_write_lock_flags(lock, flags) arch_write_lock(lock) diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h index 4f1bea1..a585635 100644 --- a/arch/x86/include/asm/spinlock_types.h +++ b/arch/x86/include/asm/spinlock_types.h @@ -34,6 +34,10 @@ typedef struct arch_spinlock { #define __ARCH_SPIN_LOCK_UNLOCKED { { 0 } } +#ifdef CONFIG_QUEUE_RWLOCK +#include +#else #include +#endif #endif /* _ASM_X86_SPINLOCK_TYPES_H */ -- 1.7.1 -- 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/