From 342e73b3d6fd1321d1eaaa6a935f267a300ceebd Mon Sep 17 00:00:00 2001 From: Jon Loeliger Date: Thu, 22 Sep 2005 14:55:30 -0500 Subject: [PATCH] powerpc: Merge asm-ppc*/rwsem.h Merge asm-ppc*/rwsem.h into include/asm-powerpc. Removed smp_*mb() memory barriers from the ppc32 code as they are now burried in the atomic_*() functions as suggested by Paul, implemented by Arnd, and pushed out by Becky. I am not the droid you are looking for. This patch depends on Becky's atomic.h merge patch. Signed-off-by: Jon Loeliger Signed-off-by: Kumar Gala Signed-off-by: Paul Mackerras --- include/asm-powerpc/rwsem.h | 163 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 163 insertions(+) create mode 100644 include/asm-powerpc/rwsem.h (limited to 'include/asm-powerpc/rwsem.h') diff --git a/include/asm-powerpc/rwsem.h b/include/asm-powerpc/rwsem.h new file mode 100644 index 000000000000..0a5b83a3c949 --- /dev/null +++ b/include/asm-powerpc/rwsem.h @@ -0,0 +1,163 @@ +#ifndef _ASM_POWERPC_RWSEM_H +#define _ASM_POWERPC_RWSEM_H + +#ifdef __KERNEL__ + +/* + * include/asm-ppc64/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 . + */ + +#include +#include +#include +#include + +/* + * the semaphore definition + */ +struct rw_semaphore { + /* XXX this should be able to be an atomic_t -- paulus */ + signed int 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); +extern struct rw_semaphore *rwsem_downgrade_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 (unlikely(atomic_inc_return((atomic_t *)(&sem->count)) <= 0)) + 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)) { + 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 (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS)) + 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); + return tmp == RWSEM_UNLOCKED_VALUE; +} + +/* + * unlock after reading + */ +static inline void __up_read(struct rw_semaphore *sem) +{ + int tmp; + + tmp = atomic_dec_return((atomic_t *)(&sem->count)); + if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)) + rwsem_wake(sem); +} + +/* + * unlock after writing + */ +static inline void __up_write(struct rw_semaphore *sem) +{ + if (unlikely(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; + + tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count)); + if (tmp < 0) + rwsem_downgrade_wake(sem); +} + +/* + * implement exchange and add functionality + */ +static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem) +{ + return atomic_add_return(delta, (atomic_t *)(&sem->count)); +} + +#endif /* __KERNEL__ */ +#endif /* _ASM_POWERPC_RWSEM_H */ -- cgit v1.2.2