patch-2.4.5 linux/include/asm-ppc/rwsem.h

• Lines: 138
• Date: Mon May 21 15:02:06 2001
• Orig file: v2.4.4/linux/include/asm-ppc/rwsem.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.4/linux/include/asm-ppc/rwsem.h linux/include/asm-ppc/rwsem.h
@@ -0,0 +1,137 @@
+/*
+ * BK Id: SCCS/s.rwsem.h 1.6 05/17/01 18:14:25 cort
+ */
+/*
+ * include/asm-ppc/rwsem.h: R/W semaphores for PPC using the stuff
+ * in lib/rwsem.c.  Adapted largely from include/asm-i386/rwsem.h
+ * by Paul Mackerras <paulus@samba.org>.
+ */
+
+#ifndef _PPC_RWSEM_H
+#define _PPC_RWSEM_H
+
+#ifdef __KERNEL__
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <asm/atomic.h>
+#include <asm/system.h>
+
+/*
+ * the semaphore definition
+ */
+struct rw_semaphore {
+	/* XXX this should be able to be an atomic_t  -- paulus */
+	signed long		count;
+#define RWSEM_UNLOCKED_VALUE		0x00000000
+#define RWSEM_ACTIVE_BIAS		0x00000001
+#define RWSEM_ACTIVE_MASK		0x0000ffff
+#define RWSEM_WAITING_BIAS		(-0x00010000)
+#define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS
+#define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
+	spinlock_t		wait_lock;
+	struct list_head	wait_list;
+#if RWSEM_DEBUG
+	int			debug;
+#endif
+};
+
+/*
+ * initialisation
+ */
+#if RWSEM_DEBUG
+#define __RWSEM_DEBUG_INIT      , 0
+#else
+#define __RWSEM_DEBUG_INIT	/* */
+#endif
+
+#define __RWSEM_INITIALIZER(name) \
+	{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \
+	  LIST_HEAD_INIT((name).wait_list) \
+	  __RWSEM_DEBUG_INIT }
+
+#define DECLARE_RWSEM(name)		\
+	struct rw_semaphore name = __RWSEM_INITIALIZER(name)
+
+extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem);
+extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem);
+extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem);
+
+static inline void init_rwsem(struct rw_semaphore *sem)
+{
+	sem->count = RWSEM_UNLOCKED_VALUE;
+	spin_lock_init(&sem->wait_lock);
+	INIT_LIST_HEAD(&sem->wait_list);
+#if RWSEM_DEBUG
+	sem->debug = 0;
+#endif
+}
+
+/*
+ * lock for reading
+ */
+static inline void __down_read(struct rw_semaphore *sem)
+{
+	if (atomic_inc_return((atomic_t *)(&sem->count)) >= 0)
+		smp_wmb();
+	else
+		rwsem_down_read_failed(sem);
+}
+
+/*
+ * lock for writing
+ */
+static inline void __down_write(struct rw_semaphore *sem)
+{
+	int tmp;
+
+	tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
+				(atomic_t *)(&sem->count));
+	if (tmp == RWSEM_ACTIVE_WRITE_BIAS)
+		smp_wmb();
+	else
+		rwsem_down_write_failed(sem);
+}
+
+/*
+ * unlock after reading
+ */
+static inline void __up_read(struct rw_semaphore *sem)
+{
+	int tmp;
+
+	smp_wmb();
+	tmp = atomic_dec_return((atomic_t *)(&sem->count));
+	if (tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)
+		rwsem_wake(sem);
+}
+
+/*
+ * unlock after writing
+ */
+static inline void __up_write(struct rw_semaphore *sem)
+{
+	smp_wmb();
+	if (atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
+			      (atomic_t *)(&sem->count)) < 0)
+		rwsem_wake(sem);
+}
+
+/*
+ * implement atomic add functionality
+ */
+static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
+{
+	atomic_add(delta, (atomic_t *)(&sem->count));
+}
+
+/*
+ * implement exchange and add functionality
+ */
+static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
+{
+	smp_mb();
+	return atomic_add_return(delta, (atomic_t *)(&sem->count));
+}
+
+#endif /* __KERNEL__ */
+#endif /* _PPC_RWSEM_XADD_H */