Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754993Ab3JXXyO (ORCPT ); Thu, 24 Oct 2013 19:54:14 -0400 Received: from g4t0016.houston.hp.com ([15.201.24.19]:38756 "EHLO g4t0016.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753782Ab3JXXyL (ORCPT ); Thu, 24 Oct 2013 19:54:11 -0400 From: Waiman Long To: Ingo Molnar , Andrew Morton , Thomas Gleixner Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Rik van Riel , Peter Hurley , Davidlohr Bueso , Alex Shi , Tim Chen , Linus Torvalds , Peter Zijlstra , Andrea Arcangeli , Matthew R Wilcox , Dave Hansen , Michel Lespinasse , Andi Kleen , Raghavendra K T , "Paul E. McKenney" , George Spelvin , "H. Peter Anvin" , Arnd Bergmann , Aswin Chandramouleeswaran , Scott J Norton , Davidlohr Bueso , Jason Low , Waiman Long Subject: [PATCH v8.1 10/10] MCS Lock: Make mcs_spinlock.h includable in other files Date: Thu, 24 Oct 2013 19:53:29 -0400 Message-Id: <1382658809-21749-1-git-send-email-Waiman.Long@hp.com> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4483 Lines: 129 The following changes are made to enable mcs_spinlock.h file to be widely included in other files without causing problem: 1) Include a number of prerequisite header files and define arch_mutex_cpu_relax(), if not previously defined. 2) Make mcs_spin_unlock() an inlined function and rename mcs_spin_lock() to _raw_mcs_spin_lock() which is also an inlined function. 3) Create a new mcs_spinlock.c file to contain the non-inlined mcs_spin_lock() function. Signed-off-by: Waiman Long --- include/linux/mcs_spinlock.h | 27 ++++++++++++++++++++++----- kernel/Makefile | 6 +++--- kernel/mcs_spinlock.c | 21 +++++++++++++++++++++ 3 files changed, 46 insertions(+), 8 deletions(-) create mode 100644 kernel/mcs_spinlock.c diff --git a/include/linux/mcs_spinlock.h b/include/linux/mcs_spinlock.h index 93d445d..f2c71e8 100644 --- a/include/linux/mcs_spinlock.h +++ b/include/linux/mcs_spinlock.h @@ -12,11 +12,27 @@ #ifndef __LINUX_MCS_SPINLOCK_H #define __LINUX_MCS_SPINLOCK_H +/* + * asm/processor.h may define arch_mutex_cpu_relax(). + * If it is not defined, cpu_relax() will be used. + */ +#include +#include +#include +#include + +#ifndef arch_mutex_cpu_relax +# define arch_mutex_cpu_relax() cpu_relax() +#endif + struct mcs_spinlock { struct mcs_spinlock *next; int locked; /* 1 if lock acquired */ }; +extern +void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node); + /* * In order to acquire the lock, the caller should declare a local node and * pass a reference of the node to this function in addition to the lock. @@ -24,11 +40,11 @@ struct mcs_spinlock { * on this node->locked until the previous lock holder sets the node->locked * in mcs_spin_unlock(). * - * We don't inline mcs_spin_lock() so that perf can correctly account for the - * time spent in this lock function. + * The _raw_mcs_spin_lock() function should not be called directly. Instead, + * users should call mcs_spin_lock(). */ -static noinline -void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node) +static inline +void _raw_mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node) { struct mcs_spinlock *prev; @@ -55,7 +71,8 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node) * Releases the lock. The caller should pass in the corresponding node that * was used to acquire the lock. */ -static void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node) +static inline +void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node) { struct mcs_spinlock *next = ACCESS_ONCE(node->next); diff --git a/kernel/Makefile b/kernel/Makefile index 1ce4755..2ad8454 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -50,9 +50,9 @@ obj-$(CONFIG_SMP) += smp.o ifneq ($(CONFIG_SMP),y) obj-y += up.o endif -obj-$(CONFIG_SMP) += spinlock.o -obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o -obj-$(CONFIG_PROVE_LOCKING) += spinlock.o +obj-$(CONFIG_SMP) += spinlock.o mcs_spinlock.o +obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o mcs_spinlock.o +obj-$(CONFIG_PROVE_LOCKING) += spinlock.o mcs_spinlock.o obj-$(CONFIG_UID16) += uid16.o obj-$(CONFIG_MODULES) += module.o obj-$(CONFIG_MODULE_SIG) += module_signing.o modsign_pubkey.o modsign_certificate.o diff --git a/kernel/mcs_spinlock.c b/kernel/mcs_spinlock.c new file mode 100644 index 0000000..309dd42 --- /dev/null +++ b/kernel/mcs_spinlock.c @@ -0,0 +1,21 @@ +/* + * MCS lock + * + * The MCS lock (proposed by Mellor-Crummey and Scott) is a simple spin-lock + * with the desirable properties of being fair, and with each cpu trying + * to acquire the lock spinning on a local variable. + * It avoids expensive cache bouncings that common test-and-set spin-lock + * implementations incur. + */ +#include +#include + +/* + * We don't inline mcs_spin_lock() so that perf can correctly account for the + * time spent in this lock function. + */ +void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node) +{ + _raw_mcs_spin_lock(lock, node); +} +EXPORT_SYMBOL(mcs_spin_lock); -- 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/