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Diffstat (limited to 'include/asm-ia64/rwsem.h')
| -rw-r--r-- | include/asm-ia64/rwsem.h | 188 |
1 files changed, 0 insertions, 188 deletions
diff --git a/include/asm-ia64/rwsem.h b/include/asm-ia64/rwsem.h deleted file mode 100644 index 6ece5061dc1..00000000000 --- a/include/asm-ia64/rwsem.h +++ /dev/null @@ -1,188 +0,0 @@ -/* - * asm-ia64/rwsem.h: R/W semaphores for ia64 - * - * Copyright (C) 2003 Ken Chen <kenneth.w.chen@intel.com> - * Copyright (C) 2003 Asit Mallick <asit.k.mallick@intel.com> - * - * Based on asm-i386/rwsem.h and other architecture implementation. - * - * The MSW of the count is the negated number of active writers and - * waiting lockers, and the LSW is the total number of active locks. - * - * The lock count is initialized to 0 (no active and no waiting lockers). - * - * When a writer subtracts WRITE_BIAS, it'll get 0xffff0001 for the case - * of an uncontended lock. Readers increment by 1 and see a positive value - * when uncontended, negative if there are writers (and maybe) readers - * waiting (in which case it goes to sleep). - */ - -#ifndef _ASM_IA64_RWSEM_H -#define _ASM_IA64_RWSEM_H - -#include <linux/list.h> -#include <linux/spinlock.h> - -#include <asm/intrinsics.h> - -/* - * the semaphore definition - */ -struct rw_semaphore { - signed int count; - spinlock_t wait_lock; - struct list_head wait_list; -#if RWSEM_DEBUG - int debug; -#endif -}; - -#define RWSEM_UNLOCKED_VALUE 0x00000000 -#define RWSEM_ACTIVE_BIAS 0x00000001 -#define RWSEM_ACTIVE_MASK 0x0000ffff -#define RWSEM_WAITING_BIAS (-0x00010000) -#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS -#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) - -/* - * initialization - */ -#if RWSEM_DEBUG -#define __RWSEM_DEBUG_INIT , 0 -#else -#define __RWSEM_DEBUG_INIT /* */ -#endif - -#define __RWSEM_INITIALIZER(name) \ - { RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \ - LIST_HEAD_INIT((name).wait_list) \ - __RWSEM_DEBUG_INIT } - -#define DECLARE_RWSEM(name) \ - struct rw_semaphore name = __RWSEM_INITIALIZER(name) - -extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem); -extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem); -extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem); -extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem); - -static inline void -init_rwsem (struct rw_semaphore *sem) -{ - sem->count = RWSEM_UNLOCKED_VALUE; - spin_lock_init(&sem->wait_lock); - INIT_LIST_HEAD(&sem->wait_list); -#if RWSEM_DEBUG - sem->debug = 0; -#endif -} - -/* - * lock for reading - */ -static inline void -__down_read (struct rw_semaphore *sem) -{ - int result = ia64_fetchadd4_acq((unsigned int *)&sem->count, 1); - - if (result < 0) - rwsem_down_read_failed(sem); -} - -/* - * lock for writing - */ -static inline void -__down_write (struct rw_semaphore *sem) -{ - int old, new; - - do { - old = sem->count; - new = old + RWSEM_ACTIVE_WRITE_BIAS; - } while (cmpxchg_acq(&sem->count, old, new) != old); - - if (old != 0) - rwsem_down_write_failed(sem); -} - -/* - * unlock after reading - */ -static inline void -__up_read (struct rw_semaphore *sem) -{ - int result = ia64_fetchadd4_rel((unsigned int *)&sem->count, -1); - - if (result < 0 && (--result & RWSEM_ACTIVE_MASK) == 0) - rwsem_wake(sem); -} - -/* - * unlock after writing - */ -static inline void -__up_write (struct rw_semaphore *sem) -{ - int old, new; - - do { - old = sem->count; - new = old - RWSEM_ACTIVE_WRITE_BIAS; - } while (cmpxchg_rel(&sem->count, old, new) != old); - - if (new < 0 && (new & RWSEM_ACTIVE_MASK) == 0) - rwsem_wake(sem); -} - -/* - * trylock for reading -- returns 1 if successful, 0 if contention - */ -static inline int -__down_read_trylock (struct rw_semaphore *sem) -{ - int tmp; - while ((tmp = sem->count) >= 0) { - if (tmp == cmpxchg_acq(&sem->count, tmp, tmp+1)) { - return 1; - } - } - return 0; -} - -/* - * trylock for writing -- returns 1 if successful, 0 if contention - */ -static inline int -__down_write_trylock (struct rw_semaphore *sem) -{ - int tmp = cmpxchg_acq(&sem->count, RWSEM_UNLOCKED_VALUE, - RWSEM_ACTIVE_WRITE_BIAS); - return tmp == RWSEM_UNLOCKED_VALUE; -} - -/* - * downgrade write lock to read lock - */ -static inline void -__downgrade_write (struct rw_semaphore *sem) -{ - int old, new; - - do { - old = sem->count; - new = old - RWSEM_WAITING_BIAS; - } while (cmpxchg_rel(&sem->count, old, new) != old); - - if (old < 0) - rwsem_downgrade_wake(sem); -} - -/* - * Implement atomic add functionality. These used to be "inline" functions, but GCC v3.1 - * doesn't quite optimize this stuff right and ends up with bad calls to fetchandadd. - */ -#define rwsem_atomic_add(delta, sem) atomic_add(delta, (atomic_t *)(&(sem)->count)) -#define rwsem_atomic_update(delta, sem) atomic_add_return(delta, (atomic_t *)(&(sem)->count)) - -#endif /* _ASM_IA64_RWSEM_H */ |