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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 <Waiman.Long@hp.com>
[peterz: near complete rewrite]
Signed-off-by: Peter 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: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.1
Waiman Long 2014-02-03 13:18:57 +01:00 committed by Ingo Molnar
parent 70af2f8a4f
commit bd01ec1a13
4 changed files with 26 additions and 0 deletions
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1
arch/x86/Kconfig
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@ -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

17
arch/x86/include/asm/qrwlock.h 100644
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@ -0,0 +1,17 @@
#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 */

4
arch/x86/include/asm/spinlock.h
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@ -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)

4
arch/x86/include/asm/spinlock_types.h
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@ -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 */