/* * include/asm-s390/spinlock.h * * S390 version * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com) * * Derived from "include/asm-i386/spinlock.h" */ #ifndef __ASM_SPINLOCK_H #define __ASM_SPINLOCK_H #include <linux/smp.h> #if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 2) static inline int _raw_compare_and_swap(volatile unsigned int *lock, unsigned int old, unsigned int new) { asm volatile( " cs %0,%3,%1" : "=d" (old), "=Q" (*lock) : "0" (old), "d" (new), "Q" (*lock) : "cc", "memory" ); return old; } #else /* __GNUC__ */ static inline int _raw_compare_and_swap(volatile unsigned int *lock, unsigned int old, unsigned int new) { asm volatile( " cs %0,%3,0(%4)" : "=d" (old), "=m" (*lock) : "0" (old), "d" (new), "a" (lock), "m" (*lock) : "cc", "memory" ); return old; } #endif /* __GNUC__ */ /* * Simple spin lock operations. There are two variants, one clears IRQ's * on the local processor, one does not. * * We make no fairness assumptions. They have a cost. * * (the type definitions are in asm/spinlock_types.h) */ #define __raw_spin_is_locked(x) ((x)->owner_cpu != 0) #define __raw_spin_unlock_wait(lock) \ do { while (__raw_spin_is_locked(lock)) \ _raw_spin_relax(lock); } while (0) extern void _raw_spin_lock_wait(raw_spinlock_t *); extern void _raw_spin_lock_wait_flags(raw_spinlock_t *, unsigned long flags); extern int _raw_spin_trylock_retry(raw_spinlock_t *); extern void _raw_spin_relax(raw_spinlock_t *lock); static inline void __raw_spin_lock(raw_spinlock_t *lp) { int old; old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id()); if (likely(old == 0)) return; _raw_spin_lock_wait(lp); } static inline void __raw_spin_lock_flags(raw_spinlock_t *lp, unsigned long flags) { int old; old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id()); if (likely(old == 0)) return; _raw_spin_lock_wait_flags(lp, flags); } static inline int __raw_spin_trylock(raw_spinlock_t *lp) { int old; old = _raw_compare_and_swap(&lp->owner_cpu, 0, ~smp_processor_id()); if (likely(old == 0)) return 1; return _raw_spin_trylock_retry(lp); } static inline void __raw_spin_unlock(raw_spinlock_t *lp) { _raw_compare_and_swap(&lp->owner_cpu, lp->owner_cpu, 0); } /* * Read-write spinlocks, allowing multiple readers * but only one writer. * * NOTE! it is quite common to have readers in interrupts * but no interrupt writers. For those circumstances we * can "mix" irq-safe locks - any writer needs to get a * irq-safe write-lock, but readers can get non-irqsafe * read-locks. */ /** * read_can_lock - would read_trylock() succeed? * @lock: the rwlock in question. */ #define __raw_read_can_lock(x) ((int)(x)->lock >= 0) /** * write_can_lock - would write_trylock() succeed? * @lock: the rwlock in question. */ #define __raw_write_can_lock(x) ((x)->lock == 0) extern void _raw_read_lock_wait(raw_rwlock_t *lp); extern int _raw_read_trylock_retry(raw_rwlock_t *lp); extern void _raw_write_lock_wait(raw_rwlock_t *lp); extern int _raw_write_trylock_retry(raw_rwlock_t *lp); static inline void __raw_read_lock(raw_rwlock_t *rw) { unsigned int old; old = rw->lock & 0x7fffffffU; if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old) _raw_read_lock_wait(rw); } static inline void __raw_read_unlock(raw_rwlock_t *rw) { unsigned int old, cmp; old = rw->lock; do { cmp = old; old = _raw_compare_and_swap(&rw->lock, old, old - 1); } while (cmp != old); } static inline void __raw_write_lock(raw_rwlock_t *rw) { if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0)) _raw_write_lock_wait(rw); } static inline void __raw_write_unlock(raw_rwlock_t *rw) { _raw_compare_and_swap(&rw->lock, 0x80000000, 0); } static inline int __raw_read_trylock(raw_rwlock_t *rw) { unsigned int old; old = rw->lock & 0x7fffffffU; if (likely(_raw_compare_and_swap(&rw->lock, old, old + 1) == old)) return 1; return _raw_read_trylock_retry(rw); } static inline int __raw_write_trylock(raw_rwlock_t *rw) { if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)) return 1; return _raw_write_trylock_retry(rw); } #define _raw_read_relax(lock) cpu_relax() #define _raw_write_relax(lock) cpu_relax() #endif /* __ASM_SPINLOCK_H */