patch-2.4.4 linux/include/asm-ia64/semaphore.h

• Lines: 217
• Date: Tue Apr 17 17:19:31 2001
• Orig file: v2.4.3/linux/include/asm-ia64/semaphore.h
• Orig date: Mon Oct 9 17:55:00 2000

diff -u --recursive --new-file v2.4.3/linux/include/asm-ia64/semaphore.h linux/include/asm-ia64/semaphore.h
@@ -7,6 +7,7 @@
  */
 
 #include <linux/wait.h>
+#include <linux/rwsem.h>
 
 #include <asm/atomic.h>
 
@@ -116,208 +117,6 @@
 #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).  BIAS must be
- * chosen such that subtracting BIAS once per CPU will result either
- * in zero (uncontended case) or in a negative value (contention
- * case).  On the other hand, BIAS must be at least as big as the
- * number of processes in the system.
- *
- * On IA-64, we use a BIAS value of 0x100000000, which supports up to
- * 2 billion (2^31) processors and 4 billion processes.
- *
- * In terms of fairness, when there is heavy use of the lock, we want
- * to see the lock being passed back and forth between readers and
- * writers (like in a producer/consumer style of communication).
- *
- *	      -ben (with clarifications & IA-64 comments by davidm)
- */
-#define RW_LOCK_BIAS		0x100000000ul
-
-struct rw_semaphore {
-	volatile long		count;
-	volatile __u8		write_bias_granted;
-	volatile __u8		read_bias_granted;
-	__u16			pad1;
-	__u32			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 __RWSEM_INITIALIZER(name,count)						\
-{										\
-	(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 void __down_read_failed (struct rw_semaphore *sem, long count);
-extern void __down_write_failed (struct rw_semaphore *sem, long count);
-extern void __rwsem_wake (struct rw_semaphore *sem, long count);
-
-static inline void
-init_rwsem (struct rw_semaphore *sem)
-{
-	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
-}
-
-static inline void
-down_read (struct rw_semaphore *sem)
-{
-	long count;
-
-#if WAITQUEUE_DEBUG
-	CHECK_MAGIC(sem->__magic);
-#endif
-
-	count = ia64_fetch_and_add(-1, &sem->count);
-	if (count < 0)
-		__down_read_failed(sem, count);
-
-#if WAITQUEUE_DEBUG
-	if (sem->write_bias_granted)
-		BUG();
-	if (atomic_read(&sem->writers))
-		BUG();
-	atomic_inc(&sem->readers);
-#endif
-}
-
-static inline void
-down_write (struct rw_semaphore *sem)
-{
-	long old_count, new_count;
-
-#if WAITQUEUE_DEBUG
-	CHECK_MAGIC(sem->__magic);
-#endif
-
-	do {
-		old_count = sem->count;
-		new_count = old_count - RW_LOCK_BIAS;
-	} while (cmpxchg_acq(&sem->count, old_count, new_count) != old_count);
-
-	if (new_count != 0)
-		__down_write_failed(sem, new_count);
-#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.
- */
-static inline void
-__up_read (struct rw_semaphore *sem)
-{
-	long count;
-
-	count = ia64_fetch_and_add(1, &sem->count);
-	if (count == 0)
-		/*
-		 * Other processes are blocked already; resolve
-		 * contention by letting either a writer or a reader
-		 * proceed...
-		 */
-		__rwsem_wake(sem, count);
-}
-
-/*
- * Releasing the writer is easy -- just release it and
- * wake up any sleepers.
- */
-static inline void
-__up_write (struct rw_semaphore *sem)
-{
-	long old_count, new_count;
-
-	do {
-		old_count = sem->count;
-		new_count = old_count + RW_LOCK_BIAS;
-	} while (cmpxchg_rel(&sem->count, old_count, new_count) != old_count);
-
-	/*
-	 * Note: new_count <u RW_LOCK_BIAS <=> old_count < 0 && new_count >= 0.
-	 *	 (where <u is "unsigned less-than").
-	 */
-	if ((unsigned long) new_count < RW_LOCK_BIAS)
-		/* someone is blocked already, resolve contention... */
-		__rwsem_wake(sem, new_count);
-}
-
-static 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);
-}
-
-static 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_IA64_SEMAPHORE_H */