patch-2.4.2 linux/include/asm-s390x/semaphore.h

• Lines: 192
• Date: Tue Feb 13 14:13:44 2001
• Orig file: v2.4.1/linux/include/asm-s390x/semaphore.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.1/linux/include/asm-s390x/semaphore.h linux/include/asm-s390x/semaphore.h
@@ -0,0 +1,191 @@
+/*
+ *  include/asm-s390/semaphore.h
+ *
+ *  S390 version
+ *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ *
+ *  Derived from "include/asm-i386/semaphore.h"
+ *    (C) Copyright 1996 Linus Torvalds
+ */
+
+#ifndef _S390_SEMAPHORE_H
+#define _S390_SEMAPHORE_H
+
+#include <asm/system.h>
+#include <asm/atomic.h>
+#include <linux/wait.h>
+
+struct semaphore {
+	atomic_t count;
+	int sleepers;
+	wait_queue_head_t wait;
+};
+
+#define __SEM_DEBUG_INIT(name)
+
+#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)
+
+static inline void sema_init (struct semaphore *sem, int val)
+{
+	*sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
+}
+
+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);
+
+static inline void down(struct semaphore * sem)
+{
+	if (atomic_dec_return(&sem->count) < 0)
+		__down(sem);
+}
+
+static inline int down_interruptible(struct semaphore * sem)
+{
+	int ret = 0;
+
+	if (atomic_dec_return(&sem->count) < 0)
+		ret = __down_interruptible(sem);
+	return ret;
+}
+
+static inline int down_trylock(struct semaphore * sem)
+{
+	int ret = 0;
+
+	if (atomic_dec_return(&sem->count) < 0)
+		ret = __down_trylock(sem);
+	return ret;
+}
+
+static inline void up(struct semaphore * sem)
+{
+	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 int	write_bias_granted;
+	volatile unsigned int	read_bias_granted;
+	wait_queue_head_t	wait;
+	wait_queue_head_t	write_bias_wait;
+};
+
+#define RW_LOCK_BIAS		 0x01000000
+
+#define __RWSEM_DEBUG_INIT	/* */
+
+#define __RWSEM_INITIALIZER(name,count) \
+{ ATOMIC_INIT(count), 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)
+
+static 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);
+}
+
+extern void __down_read_failed(int, struct rw_semaphore *);
+extern void __down_write_failed(int, struct rw_semaphore *);
+extern void __rwsem_wake(int, struct rw_semaphore *);
+
+static inline void down_read(struct rw_semaphore *sem)
+{
+	int count;
+	count = atomic_dec_return(&sem->count);
+	if (count < 0)
+		__down_read_failed(count, sem);
+}
+
+static inline void down_write(struct rw_semaphore *sem)
+{
+	int count;
+	count = atomic_add_return (-RW_LOCK_BIAS, &sem->count);
+	if (count < 0)
+		__down_write_failed(count, sem);
+}
+
+/* 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;
+	count = atomic_inc_return(&sem->count);
+	if (count == 0)
+		__rwsem_wake(count, sem);
+}
+
+/* releasing the writer is easy -- just release it and
+ * wake up any sleepers.
+ */
+static inline void up_write(struct rw_semaphore *sem)
+{
+	int count;
+	count = atomic_add_return(RW_LOCK_BIAS, &sem->count);
+	if (count >= 0 && count < RW_LOCK_BIAS)
+		__rwsem_wake(count, sem);
+}
+
+#endif