From f15cbe6f1a4b4d9df59142fc8e4abb973302cf44 Mon Sep 17 00:00:00 2001 From: Paul Mundt Date: Tue, 29 Jul 2008 08:09:44 +0900 Subject: sh: migrate to arch/sh/include/ This follows the sparc changes a439fe51a1f8eb087c22dd24d69cebae4a3addac. Most of the moving about was done with Sam's directions at: http://marc.info/?l=linux-sh&m=121724823706062&w=2 with subsequent hacking and fixups entirely my fault. Signed-off-by: Sam Ravnborg Signed-off-by: Paul Mundt --- arch/sh/include/asm/rwsem.h | 188 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 188 insertions(+) create mode 100644 arch/sh/include/asm/rwsem.h (limited to 'arch/sh/include/asm/rwsem.h') diff --git a/arch/sh/include/asm/rwsem.h b/arch/sh/include/asm/rwsem.h new file mode 100644 index 00000000000..1987f3ea7f1 --- /dev/null +++ b/arch/sh/include/asm/rwsem.h @@ -0,0 +1,188 @@ +/* + * include/asm-sh/rwsem.h: R/W semaphores for SH using the stuff + * in lib/rwsem.c. + */ + +#ifndef _ASM_SH_RWSEM_H +#define _ASM_SH_RWSEM_H + +#ifndef _LINUX_RWSEM_H +#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead" +#endif + +#ifdef __KERNEL__ +#include +#include +#include +#include + +/* + * the semaphore definition + */ +struct rw_semaphore { + 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; +#ifdef CONFIG_DEBUG_LOCK_ALLOC + struct lockdep_map dep_map; +#endif +}; + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname } +#else +# define __RWSEM_DEP_MAP_INIT(lockname) +#endif + +#define __RWSEM_INITIALIZER(name) \ + { RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \ + LIST_HEAD_INIT((name).wait_list) \ + __RWSEM_DEP_MAP_INIT(name) } + +#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); + +#define init_rwsem(sem) \ +do { \ + static struct lock_class_key __key; \ + \ + __init_rwsem((sem), #sem, &__key); \ +} while (0) + +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); +} + +/* + * 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); +} + +static inline int __down_read_trylock(struct rw_semaphore *sem) +{ + int tmp; + + while ((tmp = sem->count) >= 0) { + if (tmp == cmpxchg(&sem->count, tmp, + tmp + RWSEM_ACTIVE_READ_BIAS)) { + smp_wmb(); + return 1; + } + } + return 0; +} + +/* + * 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); +} + +static inline int __down_write_trylock(struct rw_semaphore *sem) +{ + int tmp; + + tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE, + RWSEM_ACTIVE_WRITE_BIAS); + smp_wmb(); + return tmp == RWSEM_UNLOCKED_VALUE; +} + +/* + * 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)); +} + +/* + * downgrade write lock to read lock + */ +static inline void __downgrade_write(struct rw_semaphore *sem) +{ + int tmp; + + smp_wmb(); + tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count)); + if (tmp < 0) + rwsem_downgrade_wake(sem); +} + +static inline void __down_write_nested(struct rw_semaphore *sem, int subclass) +{ + __down_write(sem); +} + +/* + * 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)); +} + +static inline int rwsem_is_locked(struct rw_semaphore *sem) +{ + return (sem->count != 0); +} + +#endif /* __KERNEL__ */ +#endif /* _ASM_SH_RWSEM_H */ -- cgit v1.2.3