patch-2.4.4 linux/include/asm-mips64/semaphore.h

• Lines: 189
• Date: Tue Apr 17 17:19:31 2001
• Orig file: v2.4.3/linux/include/asm-mips64/semaphore.h
• Orig date: Tue Nov 28 21:42:04 2000

diff -u --recursive --new-file v2.4.3/linux/include/asm-mips64/semaphore.h linux/include/asm-mips64/semaphore.h
@@ -13,6 +13,7 @@
 #include <asm/atomic.h>
 #include <linux/spinlock.h>
 #include <linux/wait.h>
+#include <linux/rwsem.h>
 
 struct semaphore {
 #ifdef __MIPSEB__
@@ -167,180 +168,6 @@
 #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 subtracting BIAS once per CPU will result
- * in the int remaining negative.  In terms of fairness, this should result
- * in the lock flopping back and forth between readers and writers under
- * heavy use.
- *
- * Once we start supporting machines with more than 128 CPUs, we should go
- * for using a 64bit atomic type instead of 32bit as counter. We shall
- * probably go for bias 0x80000000 then, so that single sethi can set it.
- * */
-
-#define RW_LOCK_BIAS		0x01000000
-
-struct rw_semaphore {
-	atomic_t		count;
-	/* bit 0 means read bias granted;
-	   bit 1 means write bias granted.  */
-	unsigned long		granted;
-	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 __RWSEM_INITIALIZER(name,count)					\
-	{ ATOMIC_INIT(count), 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)
-
-static inline void init_rwsem(struct rw_semaphore *sem)
-{
-	atomic_set(&sem->count, RW_LOCK_BIAS);
-	sem->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
-}
-
-/* The expensive part is outlined.  */
-extern void __down_read(struct rw_semaphore *sem, int count);
-extern void __down_write(struct rw_semaphore *sem, int count);
-extern void __rwsem_wake(struct rw_semaphore *sem, unsigned long readers);
-
-static inline void down_read(struct rw_semaphore *sem)
-{
-	int count;
-
-#if WAITQUEUE_DEBUG
-	CHECK_MAGIC(sem->__magic);
-#endif
-
-	count = atomic_dec_return(&sem->count);
-	if (count < 0) {
-		__down_read(sem, count);
-	}
-	mb();
-
-#if WAITQUEUE_DEBUG
-	if (sem->granted & 2)
-		BUG();
-	if (atomic_read(&sem->writers))
-		BUG();
-	atomic_inc(&sem->readers);
-#endif
-}
-
-static inline void down_write(struct rw_semaphore *sem)
-{
-	int count;
-
-#if WAITQUEUE_DEBUG
-	CHECK_MAGIC(sem->__magic);
-#endif
-
-	count = atomic_sub_return(RW_LOCK_BIAS, &sem->count);
-	if (count) {
-		__down_write(sem, count);
-	}
-	mb();
-
-#if WAITQUEUE_DEBUG
-	if (atomic_read(&sem->writers))
-		BUG();
-	if (atomic_read(&sem->readers))
-		BUG();
-	if (sem->granted & 3)
-		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.  */
-
-static inline void up_read(struct rw_semaphore *sem)
-{
-	int count;
-
-#if WAITQUEUE_DEBUG
-	CHECK_MAGIC(sem->__magic);
-	if (sem->granted & 2)
-		BUG();
-	if (atomic_read(&sem->writers))
-		BUG();
-	atomic_dec(&sem->readers);
-#endif
-
-	mb();
-	count = atomic_inc_return(&sem->count);
-	if (count == 0) {
-		__rwsem_wake(sem, 0);
-	}
-}
-
-/*
- * Releasing the writer is easy -- just release it and wake up any sleepers.
- */
-static inline void up_write(struct rw_semaphore *sem)
-{
-	int count;
-
-#if WAITQUEUE_DEBUG
-	CHECK_MAGIC(sem->__magic);
-	if (sem->granted & 3)
-		BUG();
-	if (atomic_read(&sem->readers))
-		BUG();
-	if (atomic_read(&sem->writers) != 1)
-		BUG();
-	atomic_dec(&sem->writers);
-#endif
-
-	mb();
-	count = atomic_add_return(RW_LOCK_BIAS, &sem->count);
-	if (count - RW_LOCK_BIAS < 0 && count >= 0) {
-		/* Only do the wake if we're no longer negative.  */
-		__rwsem_wake(sem, count);
-	}
 }
 
 #endif /* _ASM_SEMAPHORE_H */