| /* |
| * 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 |
| |
| 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; |
| } |
| |
| /* |
| * 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. |
| */ |
| |
| typedef struct { |
| volatile unsigned int lock; |
| #ifdef CONFIG_PREEMPT |
| unsigned int break_lock; |
| #endif |
| } __attribute__ ((aligned (4))) spinlock_t; |
| |
| #define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 } |
| #define spin_lock_init(lp) do { (lp)->lock = 0; } while(0) |
| #define spin_unlock_wait(lp) do { barrier(); } while(((volatile spinlock_t *)(lp))->lock) |
| #define spin_is_locked(x) ((x)->lock != 0) |
| #define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock) |
| |
| extern void _raw_spin_lock_wait(spinlock_t *lp, unsigned int pc); |
| extern int _raw_spin_trylock_retry(spinlock_t *lp, unsigned int pc); |
| |
| static inline void _raw_spin_lock(spinlock_t *lp) |
| { |
| unsigned long pc = (unsigned long) __builtin_return_address(0); |
| |
| if (unlikely(_raw_compare_and_swap(&lp->lock, 0, pc) != 0)) |
| _raw_spin_lock_wait(lp, pc); |
| } |
| |
| static inline int _raw_spin_trylock(spinlock_t *lp) |
| { |
| unsigned long pc = (unsigned long) __builtin_return_address(0); |
| |
| if (likely(_raw_compare_and_swap(&lp->lock, 0, pc) == 0)) |
| return 1; |
| return _raw_spin_trylock_retry(lp, pc); |
| } |
| |
| static inline void _raw_spin_unlock(spinlock_t *lp) |
| { |
| _raw_compare_and_swap(&lp->lock, lp->lock, 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. |
| */ |
| typedef struct { |
| volatile unsigned int lock; |
| volatile unsigned long owner_pc; |
| #ifdef CONFIG_PREEMPT |
| unsigned int break_lock; |
| #endif |
| } rwlock_t; |
| |
| #define RW_LOCK_UNLOCKED (rwlock_t) { 0, 0 } |
| |
| #define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0) |
| |
| /** |
| * read_can_lock - would read_trylock() succeed? |
| * @lock: the rwlock in question. |
| */ |
| #define read_can_lock(x) ((int)(x)->lock >= 0) |
| |
| /** |
| * write_can_lock - would write_trylock() succeed? |
| * @lock: the rwlock in question. |
| */ |
| #define write_can_lock(x) ((x)->lock == 0) |
| |
| extern void _raw_read_lock_wait(rwlock_t *lp); |
| extern int _raw_read_trylock_retry(rwlock_t *lp); |
| extern void _raw_write_lock_wait(rwlock_t *lp); |
| extern int _raw_write_trylock_retry(rwlock_t *lp); |
| |
| static inline void _raw_read_lock(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(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(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(rwlock_t *rw) |
| { |
| _raw_compare_and_swap(&rw->lock, 0x80000000, 0); |
| } |
| |
| static inline int _raw_read_trylock(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(rwlock_t *rw) |
| { |
| if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0)) |
| return 1; |
| return _raw_write_trylock_retry(rw); |
| } |
| |
| #endif /* __ASM_SPINLOCK_H */ |