patch-2.4.19 linux-2.4.19/include/asm-ppc64/semaphore.h

• Lines: 136
• Date: Fri Aug 2 17:39:45 2002
• Orig file: linux-2.4.18/include/asm-ppc64/semaphore.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.18/include/asm-ppc64/semaphore.h linux-2.4.19/include/asm-ppc64/semaphore.h
@@ -0,0 +1,135 @@
+#ifndef _PPC64_SEMAPHORE_H
+#define _PPC64_SEMAPHORE_H
+
+/*
+ * Swiped from asm-sparc/semaphore.h and modified
+ * -- Cort (cort@cs.nmt.edu)
+ *
+ * Stole some rw spinlock-based semaphore stuff from asm-alpha/semaphore.h
+ * -- Ani Joshi (ajoshi@unixbox.com)
+ *
+ * Remove spinlock-based RW semaphores; RW semaphore definitions are
+ * now in rwsem.h and we use the the generic lib/rwsem.c implementation.
+ * Rework semaphores to use atomic_dec_if_positive.
+ * -- Paul Mackerras (paulus@samba.org)
+ */
+
+#ifdef __KERNEL__
+
+#include <asm/atomic.h>
+#include <asm/system.h>
+#include <linux/wait.h>
+#include <linux/rwsem.h>
+
+struct semaphore {
+	/*
+	 * Note that any negative value of count is equivalent to 0,
+	 * but additionally indicates that some process(es) might be
+	 * sleeping on `wait'.
+	 */
+	atomic_t count;
+	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), \
+	  __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)
+{
+	atomic_set(&sem->count, val);
+	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);
+}
+
+extern void __down(struct semaphore * sem);
+extern int  __down_interruptible(struct semaphore * sem);
+extern void __up(struct semaphore * sem);
+
+extern inline void down(struct semaphore * sem)
+{
+#if WAITQUEUE_DEBUG
+	CHECK_MAGIC(sem->__magic);
+#endif
+
+	/*
+	 * Try to get the semaphore, take the slow path if we fail.
+	 */
+	if (atomic_dec_return(&sem->count) < 0)
+		__down(sem);
+	smp_wmb();
+}
+
+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);
+	smp_wmb();
+	return ret;
+}
+
+extern inline int down_trylock(struct semaphore * sem)
+{
+	int ret;
+
+#if WAITQUEUE_DEBUG
+	CHECK_MAGIC(sem->__magic);
+#endif
+
+	ret = atomic_dec_if_positive(&sem->count) < 0;
+	smp_wmb();
+	return ret;
+}
+
+extern inline void up(struct semaphore * sem)
+{
+#if WAITQUEUE_DEBUG
+	CHECK_MAGIC(sem->__magic);
+#endif
+
+	smp_wmb();
+	if (atomic_inc_return(&sem->count) <= 0)
+		__up(sem);
+}
+
+#endif /* __KERNEL__ */
+
+#endif /* !(_PPC64_SEMAPHORE_H) */