Commit 2ff810a7 authored by Waiman Long's avatar Waiman Long Committed by Ingo Molnar
Browse files

locking/rwlock, x86: Clean up asm/spinlock*.h to remove old rwlock code 



As the x86 architecture now uses qrwlock for its read/write lock
implementation, it is no longer necessary to keep the old rwlock code
around. This patch removes the old rwlock code in the asm/spinlock.h
and asm/spinlock_types.h files. Now the ARCH_USE_QUEUE_RWLOCK
config parameter cannot be removed from x86/Kconfig or there will be
a compilation error.

Signed-off-by: default avatarWaiman Long <Waiman.Long@hp.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Waiman Long <Waiman.Long@hp.com>
Link: http://lkml.kernel.org/r/1408037251-45918-2-git-send-email-Waiman.Long@hp.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 31542769

arch/x86/include/asm/spinlock.h

+2 −79
Original line number Diff line number Diff line
@@ -187,7 +187,6 @@ 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.
@@ -198,91 +197,15 @@ static inline void arch_spin_unlock_wait(arch_spinlock_t *lock) 
 * irq-safe write-lock, but readers can get non-irqsafe

 * read-locks.

 *

 * On x86, we implement read-write locks as a 32-bit counter

 * with the high bit (sign) being the "contended" bit.

 * On x86, we implement read-write locks using the generic qrwlock with

 * x86 specific optimization.

 */



/**

 * read_can_lock - would read_trylock() succeed?

 * @lock: the rwlock in question.

 */

static inline int arch_read_can_lock(arch_rwlock_t *lock)

{

	return lock->lock > 0;

}



/**

 * write_can_lock - would write_trylock() succeed?

 * @lock: the rwlock in question.

 */

static inline int arch_write_can_lock(arch_rwlock_t *lock)

{

	return lock->write == WRITE_LOCK_CMP;

}



static inline void arch_read_lock(arch_rwlock_t *rw)

{

	asm volatile(LOCK_PREFIX READ_LOCK_SIZE(dec) " (%0)\n\t"

		     "jns 1f\n"

		     "call __read_lock_failed\n\t"

		     "1:\n"

		     ::LOCK_PTR_REG (rw) : "memory");

}



static inline void arch_write_lock(arch_rwlock_t *rw)

{

	asm volatile(LOCK_PREFIX WRITE_LOCK_SUB(%1) "(%0)\n\t"

		     "jz 1f\n"

		     "call __write_lock_failed\n\t"

		     "1:\n"

		     ::LOCK_PTR_REG (&rw->write), "i" (RW_LOCK_BIAS)

		     : "memory");

}



static inline int arch_read_trylock(arch_rwlock_t *lock)

{

	READ_LOCK_ATOMIC(t) *count = (READ_LOCK_ATOMIC(t) *)lock;



	if (READ_LOCK_ATOMIC(dec_return)(count) >= 0)

		return 1;

	READ_LOCK_ATOMIC(inc)(count);

	return 0;

}



static inline int arch_write_trylock(arch_rwlock_t *lock)

{

	atomic_t *count = (atomic_t *)&lock->write;



	if (atomic_sub_and_test(WRITE_LOCK_CMP, count))

		return 1;

	atomic_add(WRITE_LOCK_CMP, count);

	return 0;

}



static inline void arch_read_unlock(arch_rwlock_t *rw)

{

	asm volatile(LOCK_PREFIX READ_LOCK_SIZE(inc) " %0"

		     :"+m" (rw->lock) : : "memory");

}



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)



#undef READ_LOCK_SIZE

#undef READ_LOCK_ATOMIC

#undef WRITE_LOCK_ADD

#undef WRITE_LOCK_SUB

#undef WRITE_LOCK_CMP



#define arch_spin_relax(lock)	cpu_relax()

#define arch_read_relax(lock)	cpu_relax()

#define arch_write_relax(lock)	cpu_relax()

arch/x86/include/asm/spinlock_types.h

+0 −4
Original line number Diff line number Diff line
@@ -34,10 +34,6 @@ 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 */

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