#ifndef _ASM_PARISC_SEMAPHORE_H #define _ASM_PARISC_SEMAPHORE_H #include /* * SMP- and interrupt-safe semaphores. * * (C) Copyright 1996 Linus Torvalds * * SuperH verison by Niibe Yutaka * */ /* if you're going to use out-of-line slowpaths, use .section .lock.text, * not .text.lock or the -ffunction-sections monster will eat you alive */ #include #include #include struct semaphore { atomic_t count; int waking; wait_queue_head_t wait; #if WAITQUEUE_DEBUG long __magic; #endif }; #if WAITQUEUE_DEBUG # define __SEM_DEBUG_INIT(name) \ , (long)&(name).__magic #else # define __SEM_DEBUG_INIT(name) #endif #define __SEMAPHORE_INITIALIZER(name,count) \ { ATOMIC_INIT(count), 0, __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \ __SEM_DEBUG_INIT(name) } #define __MUTEX_INITIALIZER(name) \ __SEMAPHORE_INITIALIZER(name,1) #define __DECLARE_SEMAPHORE_GENERIC(name,count) \ struct semaphore name = __SEMAPHORE_INITIALIZER(name,count) #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) extern inline void sema_init (struct semaphore *sem, int val) { /* * *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val); * * i'd rather use the more flexible initialization above, but sadly * GCC 2.7.2.3 emits a bogus warning. EGCS doesnt. Oh well. */ atomic_set(&sem->count, val); sem->waking = 0; init_waitqueue_head(&sem->wait); #if WAITQUEUE_DEBUG sem->__magic = (long)&sem->__magic; #endif } static inline void init_MUTEX (struct semaphore *sem) { sema_init(sem, 1); } static inline void init_MUTEX_LOCKED (struct semaphore *sem) { sema_init(sem, 0); } asmlinkage void __down_failed(void /* special register calling convention */); asmlinkage int __down_failed_interruptible(void /* params in registers */); asmlinkage int __down_failed_trylock(void /* params in registers */); asmlinkage void __up_wakeup(void /* special register calling convention */); asmlinkage void __down(struct semaphore * sem); asmlinkage int __down_interruptible(struct semaphore * sem); asmlinkage int __down_trylock(struct semaphore * sem); asmlinkage void __up(struct semaphore * sem); extern spinlock_t semaphore_wake_lock; extern __inline__ void down(struct semaphore * sem) { #if WAITQUEUE_DEBUG CHECK_MAGIC(sem->__magic); #endif if (atomic_dec_return(&sem->count) < 0) __down(sem); } extern __inline__ int down_interruptible(struct semaphore * sem) { int ret = 0; #if WAITQUEUE_DEBUG CHECK_MAGIC(sem->__magic); #endif if (atomic_dec_return(&sem->count) < 0) ret = __down_interruptible(sem); return ret; } extern __inline__ int down_trylock(struct semaphore * sem) { int ret = 0; #if WAITQUEUE_DEBUG CHECK_MAGIC(sem->__magic); #endif if (atomic_dec_return(&sem->count) < 0) ret = __down_trylock(sem); return ret; } /* * Note! This is subtle. We jump to wake people up only if * the semaphore was negative (== somebody was waiting on it). */ extern __inline__ void up(struct semaphore * sem) { #if WAITQUEUE_DEBUG CHECK_MAGIC(sem->__magic); #endif if (atomic_inc_return(&sem->count) <= 0) __up(sem); } /* rw mutexes (should that be mutices? =) -- throw rw * spinlocks and semaphores together, and this is what we * end up with... * * The lock is initialized to BIAS. This way, a writer * subtracts BIAS ands gets 0 for the case of an uncontended * lock. Readers decrement by 1 and see a positive value * when uncontended, negative if there are writers waiting * (in which case it goes to sleep). * * The value 0x01000000 supports up to 128 processors and * lots of processes. BIAS must be chosen such that subl'ing * BIAS once per CPU will result in the long remaining * negative. * * In terms of fairness, this should result in the lock * flopping back and forth between readers and writers * under heavy use. * * -ben */ struct rw_semaphore { atomic_t count; volatile unsigned char write_bias_granted; volatile unsigned char read_bias_granted; volatile unsigned char pad1; volatile unsigned char pad2; wait_queue_head_t wait; wait_queue_head_t write_bias_wait; #if WAITQUEUE_DEBUG long __magic; atomic_t readers; atomic_t writers; #endif }; #if WAITQUEUE_DEBUG #define __RWSEM_DEBUG_INIT , ATOMIC_INIT(0), ATOMIC_INIT(0) #else #define __RWSEM_DEBUG_INIT /* */ #endif #define RW_LOCK_BIAS 0x01000000 #define __RWSEM_INITIALIZER(name,count) \ { ATOMIC_INIT(count), 0, 0, 0, 0, __WAIT_QUEUE_HEAD_INITIALIZER((name).wait), \ __WAIT_QUEUE_HEAD_INITIALIZER((name).write_bias_wait) \ __SEM_DEBUG_INIT(name) __RWSEM_DEBUG_INIT } #define __DECLARE_RWSEM_GENERIC(name,count) \ struct rw_semaphore name = __RWSEM_INITIALIZER(name,count) #define DECLARE_RWSEM(name) __DECLARE_RWSEM_GENERIC(name,RW_LOCK_BIAS) #define DECLARE_RWSEM_READ_LOCKED(name) __DECLARE_RWSEM_GENERIC(name,RW_LOCK_BIAS-1) #define DECLARE_RWSEM_WRITE_LOCKED(name) __DECLARE_RWSEM_GENERIC(name,0) extern inline void init_rwsem(struct rw_semaphore *sem) { atomic_set(&sem->count, RW_LOCK_BIAS); sem->read_bias_granted = 0; sem->write_bias_granted = 0; init_waitqueue_head(&sem->wait); init_waitqueue_head(&sem->write_bias_wait); #if WAITQUEUE_DEBUG sem->__magic = (long)&sem->__magic; atomic_set(&sem->readers, 0); atomic_set(&sem->writers, 0); #endif } #ifdef FIXME_WILLY_FIXME_FOR_REAL_THIS_TIME extern struct rw_semaphore *__build_read_lock(struct rw_semaphore *sem, const char *what); extern struct rw_semaphore *__build_write_lock(struct rw_semaphore *sem, const char *what); #endif /* we use FASTCALL convention for the helpers */ extern struct rw_semaphore *FASTCALL(__down_read_failed(struct rw_semaphore *sem)); extern struct rw_semaphore *FASTCALL(__down_write_failed(struct rw_semaphore *sem)); extern struct rw_semaphore *FASTCALL(__rwsem_wake(struct rw_semaphore *sem)); extern inline void down_read(struct rw_semaphore *sem) { #if WAITQUEUE_DEBUG if (sem->__magic != (long)&sem->__magic) BUG(); #endif #ifdef FIXME_WILLY_FIXME_FOR_REAL_THIS_TIME __build_read_lock(sem, "__down_read_failed"); #endif #if WAITQUEUE_DEBUG if (sem->write_bias_granted) BUG(); if (atomic_read(&sem->writers)) BUG(); atomic_inc(&sem->readers); #endif } extern inline void down_write(struct rw_semaphore *sem) { #if WAITQUEUE_DEBUG if (sem->__magic != (long)&sem->__magic) BUG(); #endif #ifdef FIXME_WILLY_FIXME_FOR_REAL_THIS_TIME __build_write_lock(sem, "__down_write_failed"); #endif #if WAITQUEUE_DEBUG if (atomic_read(&sem->writers)) BUG(); if (atomic_read(&sem->readers)) BUG(); if (sem->read_bias_granted) BUG(); if (sem->write_bias_granted) BUG(); atomic_inc(&sem->writers); #endif } /* When a reader does a release, the only significant * case is when there was a writer waiting, and we've * bumped the count to 0: we must wake the writer up. */ extern inline void __up_read(struct rw_semaphore *sem) { } /* releasing the writer is easy -- just release it and * wake up any sleepers. */ extern inline void __up_write(struct rw_semaphore *sem) { } extern inline void up_read(struct rw_semaphore *sem) { #if WAITQUEUE_DEBUG if (sem->write_bias_granted) BUG(); if (atomic_read(&sem->writers)) BUG(); atomic_dec(&sem->readers); #endif __up_read(sem); } extern inline void up_write(struct rw_semaphore *sem) { #if WAITQUEUE_DEBUG if (sem->read_bias_granted) BUG(); if (sem->write_bias_granted) BUG(); if (atomic_read(&sem->readers)) BUG(); if (atomic_read(&sem->writers) != 1) BUG(); atomic_dec(&sem->writers); #endif __up_write(sem); } #endif /* _ASM_PARISC_SEMAPHORE_H */