From bd01ec1a13f9a327950c8e3080096446c7804753 Mon Sep 17 00:00:00 2001 From: Waiman Long Date: Mon, 3 Feb 2014 13:18:57 +0100 Subject: [PATCH] x86, locking/rwlocks: Enable qrwlocks on x86 Make x86 use the fair rwlock_t. Implement the custom queue_write_unlock() for best performance. Signed-off-by: Waiman Long [peterz: near complete rewrite] Signed-off-by: Peter Zijlstra Cc: Dave Jones Cc: Jeremy Fitzhardinge Cc: Konrad Rzeszutek Wilk Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Raghavendra K T Cc: "Paul E.McKenney" Cc: linux-kernel@vger.kernel.org Cc: x86@kernel.org Link: http://lkml.kernel.org/n/tip-r1xuzmdysvuhl3h86n5fbxi7@git.kernel.org Signed-off-by: Ingo Molnar --- arch/x86/Kconfig | 1 + arch/x86/include/asm/qrwlock.h | 17 +++++++++++++++++ arch/x86/include/asm/spinlock.h | 4 ++++ arch/x86/include/asm/spinlock_types.h | 4 ++++ 4 files changed, 26 insertions(+) create mode 100644 arch/x86/include/asm/qrwlock.h diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 25d2c6f7325e..bf7626fcd363 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -121,6 +121,7 @@ config X86 select MODULES_USE_ELF_RELA if X86_64 select CLONE_BACKWARDS if X86_32 select ARCH_USE_BUILTIN_BSWAP + select ARCH_USE_QUEUE_RWLOCK select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION select OLD_SIGACTION if X86_32 select COMPAT_OLD_SIGACTION if IA32_EMULATION diff --git a/arch/x86/include/asm/qrwlock.h b/arch/x86/include/asm/qrwlock.h new file mode 100644 index 000000000000..70f46f07f94e --- /dev/null +++ b/arch/x86/include/asm/qrwlock.h @@ -0,0 +1,17 @@ +#ifndef _ASM_X86_QRWLOCK_H +#define _ASM_X86_QRWLOCK_H + +#include + +#if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE) +#define queue_write_unlock queue_write_unlock +static inline void queue_write_unlock(struct qrwlock *lock) +{ + barrier(); + ACCESS_ONCE(*(u8 *)&lock->cnts) = 0; +} +#endif + +#include + +#endif /* _ASM_X86_QRWLOCK_H */ diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index 0f62f5482d91..54f1c8068c02 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -187,6 +187,7 @@ 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. @@ -269,6 +270,9 @@ 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"); } +#else +#include +#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 4f1bea19945b..73c4c007200f 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 */ -- 2.39.5