linux-stable/include/linux/rwsem-spinlock.h
Peter Zijlstra 13b9a962a2 locking/rwsem: Rename 'activity' to 'count'
There are two definitions of struct rw_semaphore, one in linux/rwsem.h
and one in linux/rwsem-spinlock.h.

For some reason they have different names for the initial field. This
makes it impossible to use C99 named initialization for
__RWSEM_INITIALIZER() -- or we have to duplicate that entire thing
along with the structure definitions.

The simpler patch is renaming the rwsem-spinlock variant to match the
regular rwsem.

This allows us to switch to C99 named initialization.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-bmrZolsbGmautmzrerog27io@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-07-16 14:56:55 +02:00

45 lines
1.5 KiB
C

/* rwsem-spinlock.h: fallback C implementation
*
* Copyright (c) 2001 David Howells (dhowells@redhat.com).
* - Derived partially from ideas by Andrea Arcangeli <andrea@suse.de>
* - Derived also from comments by Linus
*/
#ifndef _LINUX_RWSEM_SPINLOCK_H
#define _LINUX_RWSEM_SPINLOCK_H
#ifndef _LINUX_RWSEM_H
#error "please don't include linux/rwsem-spinlock.h directly, use linux/rwsem.h instead"
#endif
#ifdef __KERNEL__
/*
* the rw-semaphore definition
* - if count is 0 then there are no active readers or writers
* - if count is +ve then that is the number of active readers
* - if count is -1 then there is one active writer
* - if wait_list is not empty, then there are processes waiting for the semaphore
*/
struct rw_semaphore {
__s32 count;
raw_spinlock_t wait_lock;
struct list_head wait_list;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
};
#define RWSEM_UNLOCKED_VALUE 0x00000000
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 void __down_write_nested(struct rw_semaphore *sem, int subclass);
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);
extern int rwsem_is_locked(struct rw_semaphore *sem);
#endif /* __KERNEL__ */
#endif /* _LINUX_RWSEM_SPINLOCK_H */