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author | Scott Wood <scottwood@freescale.com> | 2014-04-07 23:49:35 (GMT) |
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committer | Scott Wood <scottwood@freescale.com> | 2014-04-07 23:49:35 (GMT) |
commit | 62b8c978ee6b8d135d9e7953221de58000dba986 (patch) | |
tree | 683b04b2e627f6710c22c151b23c8cc9a165315e /kernel/rwsem.c | |
parent | 78fd82238d0e5716578c326404184a27ba67fd6e (diff) | |
download | linux-fsl-qoriq-62b8c978ee6b8d135d9e7953221de58000dba986.tar.xz |
Rewind v3.13-rc3+ (78fd82238d0e5716) to v3.12
Diffstat (limited to 'kernel/rwsem.c')
-rw-r--r-- | kernel/rwsem.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/kernel/rwsem.c b/kernel/rwsem.c new file mode 100644 index 0000000..cfff143 --- /dev/null +++ b/kernel/rwsem.c @@ -0,0 +1,157 @@ +/* kernel/rwsem.c: R/W semaphores, public implementation + * + * Written by David Howells (dhowells@redhat.com). + * Derived from asm-i386/semaphore.h + */ + +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/export.h> +#include <linux/rwsem.h> + +#include <linux/atomic.h> + +/* + * lock for reading + */ +void __sched down_read(struct rw_semaphore *sem) +{ + might_sleep(); + rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_); + + LOCK_CONTENDED(sem, __down_read_trylock, __down_read); +} + +EXPORT_SYMBOL(down_read); + +/* + * trylock for reading -- returns 1 if successful, 0 if contention + */ +int down_read_trylock(struct rw_semaphore *sem) +{ + int ret = __down_read_trylock(sem); + + if (ret == 1) + rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_); + return ret; +} + +EXPORT_SYMBOL(down_read_trylock); + +/* + * lock for writing + */ +void __sched down_write(struct rw_semaphore *sem) +{ + might_sleep(); + rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_); + + LOCK_CONTENDED(sem, __down_write_trylock, __down_write); +} + +EXPORT_SYMBOL(down_write); + +/* + * trylock for writing -- returns 1 if successful, 0 if contention + */ +int down_write_trylock(struct rw_semaphore *sem) +{ + int ret = __down_write_trylock(sem); + + if (ret == 1) + rwsem_acquire(&sem->dep_map, 0, 1, _RET_IP_); + return ret; +} + +EXPORT_SYMBOL(down_write_trylock); + +/* + * release a read lock + */ +void up_read(struct rw_semaphore *sem) +{ + rwsem_release(&sem->dep_map, 1, _RET_IP_); + + __up_read(sem); +} + +EXPORT_SYMBOL(up_read); + +/* + * release a write lock + */ +void up_write(struct rw_semaphore *sem) +{ + rwsem_release(&sem->dep_map, 1, _RET_IP_); + + __up_write(sem); +} + +EXPORT_SYMBOL(up_write); + +/* + * downgrade write lock to read lock + */ +void downgrade_write(struct rw_semaphore *sem) +{ + /* + * lockdep: a downgraded write will live on as a write + * dependency. + */ + __downgrade_write(sem); +} + +EXPORT_SYMBOL(downgrade_write); + +#ifdef CONFIG_DEBUG_LOCK_ALLOC + +void down_read_nested(struct rw_semaphore *sem, int subclass) +{ + might_sleep(); + rwsem_acquire_read(&sem->dep_map, subclass, 0, _RET_IP_); + + LOCK_CONTENDED(sem, __down_read_trylock, __down_read); +} + +EXPORT_SYMBOL(down_read_nested); + +void _down_write_nest_lock(struct rw_semaphore *sem, struct lockdep_map *nest) +{ + might_sleep(); + rwsem_acquire_nest(&sem->dep_map, 0, 0, nest, _RET_IP_); + + LOCK_CONTENDED(sem, __down_write_trylock, __down_write); +} + +EXPORT_SYMBOL(_down_write_nest_lock); + +void down_read_non_owner(struct rw_semaphore *sem) +{ + might_sleep(); + + __down_read(sem); +} + +EXPORT_SYMBOL(down_read_non_owner); + +void down_write_nested(struct rw_semaphore *sem, int subclass) +{ + might_sleep(); + rwsem_acquire(&sem->dep_map, subclass, 0, _RET_IP_); + + LOCK_CONTENDED(sem, __down_write_trylock, __down_write); +} + +EXPORT_SYMBOL(down_write_nested); + +void up_read_non_owner(struct rw_semaphore *sem) +{ + __up_read(sem); +} + +EXPORT_SYMBOL(up_read_non_owner); + +#endif + + |