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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: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter 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: Ingo Molnar <mingo@kernel.org>
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315427691c
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2 changed files with 2 additions and 83 deletions
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@ -187,7 +187,6 @@ static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
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cpu_relax();
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}
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#ifndef CONFIG_QUEUE_RWLOCK
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/*
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* Read-write spinlocks, allowing multiple readers
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* but only one writer.
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@ -198,91 +197,15 @@ static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
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* irq-safe write-lock, but readers can get non-irqsafe
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* read-locks.
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*
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* On x86, we implement read-write locks as a 32-bit counter
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* with the high bit (sign) being the "contended" bit.
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* On x86, we implement read-write locks using the generic qrwlock with
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* x86 specific optimization.
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*/
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/**
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* read_can_lock - would read_trylock() succeed?
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* @lock: the rwlock in question.
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*/
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static inline int arch_read_can_lock(arch_rwlock_t *lock)
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{
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return lock->lock > 0;
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}
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/**
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* write_can_lock - would write_trylock() succeed?
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* @lock: the rwlock in question.
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*/
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static inline int arch_write_can_lock(arch_rwlock_t *lock)
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{
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return lock->write == WRITE_LOCK_CMP;
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}
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static inline void arch_read_lock(arch_rwlock_t *rw)
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{
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asm volatile(LOCK_PREFIX READ_LOCK_SIZE(dec) " (%0)\n\t"
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"jns 1f\n"
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"call __read_lock_failed\n\t"
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"1:\n"
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::LOCK_PTR_REG (rw) : "memory");
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}
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static inline void arch_write_lock(arch_rwlock_t *rw)
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{
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asm volatile(LOCK_PREFIX WRITE_LOCK_SUB(%1) "(%0)\n\t"
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"jz 1f\n"
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"call __write_lock_failed\n\t"
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"1:\n"
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::LOCK_PTR_REG (&rw->write), "i" (RW_LOCK_BIAS)
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: "memory");
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}
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static inline int arch_read_trylock(arch_rwlock_t *lock)
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{
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READ_LOCK_ATOMIC(t) *count = (READ_LOCK_ATOMIC(t) *)lock;
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if (READ_LOCK_ATOMIC(dec_return)(count) >= 0)
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return 1;
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READ_LOCK_ATOMIC(inc)(count);
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return 0;
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}
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static inline int arch_write_trylock(arch_rwlock_t *lock)
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{
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atomic_t *count = (atomic_t *)&lock->write;
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if (atomic_sub_and_test(WRITE_LOCK_CMP, count))
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return 1;
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atomic_add(WRITE_LOCK_CMP, count);
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return 0;
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}
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static inline void arch_read_unlock(arch_rwlock_t *rw)
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{
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asm volatile(LOCK_PREFIX READ_LOCK_SIZE(inc) " %0"
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:"+m" (rw->lock) : : "memory");
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}
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static inline void arch_write_unlock(arch_rwlock_t *rw)
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{
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asm volatile(LOCK_PREFIX WRITE_LOCK_ADD(%1) "%0"
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: "+m" (rw->write) : "i" (RW_LOCK_BIAS) : "memory");
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}
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#else
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#include <asm/qrwlock.h>
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#endif /* CONFIG_QUEUE_RWLOCK */
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#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
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#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
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#undef READ_LOCK_SIZE
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#undef READ_LOCK_ATOMIC
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#undef WRITE_LOCK_ADD
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#undef WRITE_LOCK_SUB
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#undef WRITE_LOCK_CMP
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#define arch_spin_relax(lock) cpu_relax()
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#define arch_read_relax(lock) cpu_relax()
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#define arch_write_relax(lock) cpu_relax()
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@ -34,10 +34,6 @@ typedef struct arch_spinlock {
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#define __ARCH_SPIN_LOCK_UNLOCKED { { 0 } }
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#ifdef CONFIG_QUEUE_RWLOCK
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#include <asm-generic/qrwlock_types.h>
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#else
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#include <asm/rwlock.h>
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#endif
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#endif /* _ASM_X86_SPINLOCK_TYPES_H */
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