patch-2.4.0-test12 linux/include/asm-parisc/semaphore.h

• Lines: 302
• Date: Tue Dec 5 12:29:39 2000
• Orig file: v2.4.0-test11/linux/include/asm-parisc/semaphore.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.0-test11/linux/include/asm-parisc/semaphore.h linux/include/asm-parisc/semaphore.h
@@ -0,0 +1,301 @@
+#ifndef _ASM_PARISC_SEMAPHORE_H
+#define _ASM_PARISC_SEMAPHORE_H
+
+#include <linux/linkage.h>
+
+/*
+ * 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 <linux/spinlock.h>
+
+#include <asm/system.h>
+#include <asm/atomic.h>
+
+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 */