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