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Commit bd01ec1a authored by Waiman Long's avatar Waiman Long Committed by Ingo Molnar
Browse files

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: default avatarWaiman Long <Waiman.Long@hp.com>
[peterz: near complete rewrite]
Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: "Paul E.McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org
Cc: x86@kernel.org
Link: http://lkml.kernel.org/n/tip-r1xuzmdysvuhl3h86n5fbxi7@git.kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 70af2f8a

arch/x86/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/include/asm/qrwlock.h

0 → 100644
+17 −0
Original line number Diff line number Diff line 
#ifndef _ASM_X86_QRWLOCK_H

#define _ASM_X86_QRWLOCK_H



#include <asm-generic/qrwlock_types.h>



#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 <asm-generic/qrwlock.h>



#endif /* _ASM_X86_QRWLOCK_H */

arch/x86/include/asm/spinlock.h

+4 −0
Original line number Diff line number Diff line
@@ -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 <asm/qrwlock.h>

#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)

arch/x86/include/asm/spinlock_types.h

+4 −0
Original line number Diff line number Diff line
@@ -34,6 +34,10 @@ typedef struct arch_spinlock { 


#define __ARCH_SPIN_LOCK_UNLOCKED	{ { 0 } }



#ifdef CONFIG_QUEUE_RWLOCK

#include <asm-generic/qrwlock_types.h>

#else

#include <asm/rwlock.h>

#endif



#endif /* _ASM_X86_SPINLOCK_TYPES_H */