Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph...

[pandora-kernel.git] / arch / sparc / include / asm / rwsem.h

diff --git a/arch/sparc/include/asm/rwsem.h b/arch/sparc/include/asm/rwsem.h
index 6e56210..a2b4302 100644 (file)
--- a/arch/sparc/include/asm/rwsem.h
+++ b/arch/sparc/include/asm/rwsem.h
@@ -15,16 +15,21 @@
 
 #include <linux/list.h>
 #include <linux/spinlock.h>
-#include <asm/rwsem-const.h>
 
 struct rwsem_waiter;
 
 struct rw_semaphore {
-       signed int count;
-       spinlock_t              wait_lock;
-       struct list_head        wait_list;
+       signed long                     count;
+#define RWSEM_UNLOCKED_VALUE           0x00000000L
+#define RWSEM_ACTIVE_BIAS              0x00000001L
+#define RWSEM_ACTIVE_MASK              0xffffffffL
+#define RWSEM_WAITING_BIAS             (-RWSEM_ACTIVE_MASK-1)
+#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;
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
-       struct lockdep_map      dep_map;
+       struct lockdep_map              dep_map;
 #endif
 };
 
@@ -41,6 +46,11 @@ struct rw_semaphore {
 #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);
+extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);
+
 extern void __init_rwsem(struct rw_semaphore *sem, const char *name,
                         struct lock_class_key *key);
 
@@ -51,27 +61,103 @@ do {                                                               \
        __init_rwsem((sem), #sem, &__key);                      \
 } while (0)
 
-extern void __down_read(struct rw_semaphore *sem);
-extern int __down_read_trylock(struct rw_semaphore *sem);
-extern void __down_write(struct rw_semaphore *sem);
-extern int __down_write_trylock(struct rw_semaphore *sem);
-extern void __up_read(struct rw_semaphore *sem);
-extern void __up_write(struct rw_semaphore *sem);
-extern void __downgrade_write(struct rw_semaphore *sem);
+/*
+ * lock for reading
+ */
+static inline void __down_read(struct rw_semaphore *sem)
+{
+       if (unlikely(atomic64_inc_return((atomic64_t *)(&sem->count)) <= 0L))
+               rwsem_down_read_failed(sem);
+}
+
+static inline int __down_read_trylock(struct rw_semaphore *sem)
+{
+       long tmp;
+
+       while ((tmp = sem->count) >= 0L) {
+               if (tmp == cmpxchg(&sem->count, tmp,
+                                  tmp + RWSEM_ACTIVE_READ_BIAS)) {
+                       return 1;
+               }
+       }
+       return 0;
+}
 
+/*
+ * lock for writing
+ */
 static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
 {
-       __down_write(sem);
+       long tmp;
+
+       tmp = atomic64_add_return(RWSEM_ACTIVE_WRITE_BIAS,
+                                 (atomic64_t *)(&sem->count));
+       if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
+               rwsem_down_write_failed(sem);
 }
 
-static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
+static inline void __down_write(struct rw_semaphore *sem)
 {
-       return atomic_add_return(delta, (atomic_t *)(&sem->count));
+       __down_write_nested(sem, 0);
+}
+
+static inline int __down_write_trylock(struct rw_semaphore *sem)
+{
+       long tmp;
+
+       tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
+                     RWSEM_ACTIVE_WRITE_BIAS);
+       return tmp == RWSEM_UNLOCKED_VALUE;
 }
 
-static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
+/*
+ * unlock after reading
+ */
+static inline void __up_read(struct rw_semaphore *sem)
+{
+       long tmp;
+
+       tmp = atomic64_dec_return((atomic64_t *)(&sem->count));
+       if (unlikely(tmp < -1L && (tmp & RWSEM_ACTIVE_MASK) == 0L))
+               rwsem_wake(sem);
+}
+
+/*
+ * unlock after writing
+ */
+static inline void __up_write(struct rw_semaphore *sem)
+{
+       if (unlikely(atomic64_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
+                                        (atomic64_t *)(&sem->count)) < 0L))
+               rwsem_wake(sem);
+}
+
+/*
+ * implement atomic add functionality
+ */
+static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem)
+{
+       atomic64_add(delta, (atomic64_t *)(&sem->count));
+}
+
+/*
+ * downgrade write lock to read lock
+ */
+static inline void __downgrade_write(struct rw_semaphore *sem)
+{
+       long tmp;
+
+       tmp = atomic64_add_return(-RWSEM_WAITING_BIAS, (atomic64_t *)(&sem->count));
+       if (tmp < 0L)
+               rwsem_downgrade_wake(sem);
+}
+
+/*
+ * implement exchange and add functionality
+ */
+static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
 {
-       atomic_add(delta, (atomic_t *)(&sem->count));
+       return atomic64_add_return(delta, (atomic64_t *)(&sem->count));
 }
 
 static inline int rwsem_is_locked(struct rw_semaphore *sem)