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-rw-r--r--arch/alpha/include/asm/rwsem.h259
1 files changed, 259 insertions, 0 deletions
diff --git a/arch/alpha/include/asm/rwsem.h b/arch/alpha/include/asm/rwsem.h
new file mode 100644
index 00000000000..1570c0b5433
--- /dev/null
+++ b/arch/alpha/include/asm/rwsem.h
@@ -0,0 +1,259 @@
+#ifndef _ALPHA_RWSEM_H
+#define _ALPHA_RWSEM_H
+
+/*
+ * Written by Ivan Kokshaysky <ink@jurassic.park.msu.ru>, 2001.
+ * Based on asm-alpha/semaphore.h and asm-i386/rwsem.h
+ */
+
+#ifndef _LINUX_RWSEM_H
+#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
+#endif
+
+#ifdef __KERNEL__
+
+#include <linux/compiler.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+
+struct rwsem_waiter;
+
+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 *);
+extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);
+
+/*
+ * the semaphore definition
+ */
+struct rw_semaphore {
+ long count;
+#define RWSEM_UNLOCKED_VALUE 0x0000000000000000L
+#define RWSEM_ACTIVE_BIAS 0x0000000000000001L
+#define RWSEM_ACTIVE_MASK 0x00000000ffffffffL
+#define RWSEM_WAITING_BIAS (-0x0000000100000000L)
+#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;
+};
+
+#define __RWSEM_INITIALIZER(name) \
+ { RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \
+ LIST_HEAD_INIT((name).wait_list) }
+
+#define DECLARE_RWSEM(name) \
+ struct rw_semaphore name = __RWSEM_INITIALIZER(name)
+
+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);
+}
+
+static inline void __down_read(struct rw_semaphore *sem)
+{
+ long oldcount;
+#ifndef CONFIG_SMP
+ oldcount = sem->count;
+ sem->count += RWSEM_ACTIVE_READ_BIAS;
+#else
+ long temp;
+ __asm__ __volatile__(
+ "1: ldq_l %0,%1\n"
+ " addq %0,%3,%2\n"
+ " stq_c %2,%1\n"
+ " beq %2,2f\n"
+ " mb\n"
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
+ :"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory");
+#endif
+ if (unlikely(oldcount < 0))
+ rwsem_down_read_failed(sem);
+}
+
+/*
+ * trylock for reading -- returns 1 if successful, 0 if contention
+ */
+static inline int __down_read_trylock(struct rw_semaphore *sem)
+{
+ long old, new, res;
+
+ res = sem->count;
+ do {
+ new = res + RWSEM_ACTIVE_READ_BIAS;
+ if (new <= 0)
+ break;
+ old = res;
+ res = cmpxchg(&sem->count, old, new);
+ } while (res != old);
+ return res >= 0 ? 1 : 0;
+}
+
+static inline void __down_write(struct rw_semaphore *sem)
+{
+ long oldcount;
+#ifndef CONFIG_SMP
+ oldcount = sem->count;
+ sem->count += RWSEM_ACTIVE_WRITE_BIAS;
+#else
+ long temp;
+ __asm__ __volatile__(
+ "1: ldq_l %0,%1\n"
+ " addq %0,%3,%2\n"
+ " stq_c %2,%1\n"
+ " beq %2,2f\n"
+ " mb\n"
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
+ :"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory");
+#endif
+ if (unlikely(oldcount))
+ rwsem_down_write_failed(sem);
+}
+
+/*
+ * trylock for writing -- returns 1 if successful, 0 if contention
+ */
+static inline int __down_write_trylock(struct rw_semaphore *sem)
+{
+ long ret = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
+ RWSEM_ACTIVE_WRITE_BIAS);
+ if (ret == RWSEM_UNLOCKED_VALUE)
+ return 1;
+ return 0;
+}
+
+static inline void __up_read(struct rw_semaphore *sem)
+{
+ long oldcount;
+#ifndef CONFIG_SMP
+ oldcount = sem->count;
+ sem->count -= RWSEM_ACTIVE_READ_BIAS;
+#else
+ long temp;
+ __asm__ __volatile__(
+ " mb\n"
+ "1: ldq_l %0,%1\n"
+ " subq %0,%3,%2\n"
+ " stq_c %2,%1\n"
+ " beq %2,2f\n"
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
+ :"Ir" (RWSEM_ACTIVE_READ_BIAS), "m" (sem->count) : "memory");
+#endif
+ if (unlikely(oldcount < 0))
+ if ((int)oldcount - RWSEM_ACTIVE_READ_BIAS == 0)
+ rwsem_wake(sem);
+}
+
+static inline void __up_write(struct rw_semaphore *sem)
+{
+ long count;
+#ifndef CONFIG_SMP
+ sem->count -= RWSEM_ACTIVE_WRITE_BIAS;
+ count = sem->count;
+#else
+ long temp;
+ __asm__ __volatile__(
+ " mb\n"
+ "1: ldq_l %0,%1\n"
+ " subq %0,%3,%2\n"
+ " stq_c %2,%1\n"
+ " beq %2,2f\n"
+ " subq %0,%3,%0\n"
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ :"=&r" (count), "=m" (sem->count), "=&r" (temp)
+ :"Ir" (RWSEM_ACTIVE_WRITE_BIAS), "m" (sem->count) : "memory");
+#endif
+ if (unlikely(count))
+ if ((int)count == 0)
+ rwsem_wake(sem);
+}
+
+/*
+ * downgrade write lock to read lock
+ */
+static inline void __downgrade_write(struct rw_semaphore *sem)
+{
+ long oldcount;
+#ifndef CONFIG_SMP
+ oldcount = sem->count;
+ sem->count -= RWSEM_WAITING_BIAS;
+#else
+ long temp;
+ __asm__ __volatile__(
+ "1: ldq_l %0,%1\n"
+ " addq %0,%3,%2\n"
+ " stq_c %2,%1\n"
+ " beq %2,2f\n"
+ " mb\n"
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ :"=&r" (oldcount), "=m" (sem->count), "=&r" (temp)
+ :"Ir" (-RWSEM_WAITING_BIAS), "m" (sem->count) : "memory");
+#endif
+ if (unlikely(oldcount < 0))
+ rwsem_downgrade_wake(sem);
+}
+
+static inline void rwsem_atomic_add(long val, struct rw_semaphore *sem)
+{
+#ifndef CONFIG_SMP
+ sem->count += val;
+#else
+ long temp;
+ __asm__ __volatile__(
+ "1: ldq_l %0,%1\n"
+ " addq %0,%2,%0\n"
+ " stq_c %0,%1\n"
+ " beq %0,2f\n"
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ :"=&r" (temp), "=m" (sem->count)
+ :"Ir" (val), "m" (sem->count));
+#endif
+}
+
+static inline long rwsem_atomic_update(long val, struct rw_semaphore *sem)
+{
+#ifndef CONFIG_SMP
+ sem->count += val;
+ return sem->count;
+#else
+ long ret, temp;
+ __asm__ __volatile__(
+ "1: ldq_l %0,%1\n"
+ " addq %0,%3,%2\n"
+ " addq %0,%3,%0\n"
+ " stq_c %2,%1\n"
+ " beq %2,2f\n"
+ ".subsection 2\n"
+ "2: br 1b\n"
+ ".previous"
+ :"=&r" (ret), "=m" (sem->count), "=&r" (temp)
+ :"Ir" (val), "m" (sem->count));
+
+ return ret;
+#endif
+}
+
+static inline int rwsem_is_locked(struct rw_semaphore *sem)
+{
+ return (sem->count != 0);
+}
+
+#endif /* __KERNEL__ */
+#endif /* _ALPHA_RWSEM_H */
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