Release 4.7 include/asm-generic/rwsem.h
#ifndef _ASM_GENERIC_RWSEM_H
#define _ASM_GENERIC_RWSEM_H
#ifndef _LINUX_RWSEM_H
#error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead."
#endif
#ifdef __KERNEL__
/*
* R/W semaphores originally for PPC using the stuff in lib/rwsem.c.
* Adapted largely from include/asm-i386/rwsem.h
* by Paul Mackerras <paulus@samba.org>.
*/
/*
* the semaphore definition
*/
#ifdef CONFIG_64BIT
# define RWSEM_ACTIVE_MASK 0xffffffffL
#else
# define RWSEM_ACTIVE_MASK 0x0000ffffL
#endif
#define RWSEM_UNLOCKED_VALUE 0x00000000L
#define RWSEM_ACTIVE_BIAS 0x00000001L
#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)
/*
* lock for reading
*/
static inline void __down_read(struct rw_semaphore *sem)
{
if (unlikely(atomic_long_inc_return_acquire((atomic_long_t *)&sem->count) <= 0))
rwsem_down_read_failed(sem);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| richard kuo | richard kuo | 35 | 97.22% | 1 | 50.00% |
| davidlohr bueso | davidlohr bueso | 1 | 2.78% | 1 | 50.00% |
| Total | 36 | 100.00% | 2 | 100.00% |
static inline int __down_read_trylock(struct rw_semaphore *sem)
{
long tmp;
while ((tmp = sem->count) >= 0) {
if (tmp == cmpxchg_acquire(&sem->count, tmp,
tmp + RWSEM_ACTIVE_READ_BIAS)) {
return 1;
}
}
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| richard kuo | richard kuo | 54 | 98.18% | 1 | 50.00% |
| davidlohr bueso | davidlohr bueso | 1 | 1.82% | 1 | 50.00% |
| Total | 55 | 100.00% | 2 | 100.00% |
/*
* lock for writing
*/
static inline void __down_write(struct rw_semaphore *sem)
{
long tmp;
tmp = atomic_long_add_return_acquire(RWSEM_ACTIVE_WRITE_BIAS,
(atomic_long_t *)&sem->count);
if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
rwsem_down_write_failed(sem);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| richard kuo | richard kuo | 43 | 95.56% | 1 | 33.33% |
| davidlohr bueso | davidlohr bueso | 1 | 2.22% | 1 | 33.33% |
| michal hocko | michal hocko | 1 | 2.22% | 1 | 33.33% |
| Total | 45 | 100.00% | 3 | 100.00% |
static inline int __down_write_killable(struct rw_semaphore *sem)
{
long tmp;
tmp = atomic_long_add_return_acquire(RWSEM_ACTIVE_WRITE_BIAS,
(atomic_long_t *)&sem->count);
if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
if (IS_ERR(rwsem_down_write_failed_killable(sem)))
return -EINTR;
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| michal hocko | michal hocko | 57 | 100.00% | 1 | 100.00% |
| Total | 57 | 100.00% | 1 | 100.00% |
static inline int __down_write_trylock(struct rw_semaphore *sem)
{
long tmp;
tmp = cmpxchg_acquire(&sem->count, RWSEM_UNLOCKED_VALUE,
RWSEM_ACTIVE_WRITE_BIAS);
return tmp == RWSEM_UNLOCKED_VALUE;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| richard kuo | richard kuo | 33 | 97.06% | 1 | 50.00% |
| davidlohr bueso | davidlohr bueso | 1 | 2.94% | 1 | 50.00% |
| Total | 34 | 100.00% | 2 | 100.00% |
/*
* unlock after reading
*/
static inline void __up_read(struct rw_semaphore *sem)
{
long tmp;
tmp = atomic_long_dec_return_release((atomic_long_t *)&sem->count);
if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0))
rwsem_wake(sem);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| richard kuo | richard kuo | 51 | 98.08% | 1 | 50.00% |
| davidlohr bueso | davidlohr bueso | 1 | 1.92% | 1 | 50.00% |
| Total | 52 | 100.00% | 2 | 100.00% |
/*
* unlock after writing
*/
static inline void __up_write(struct rw_semaphore *sem)
{
if (unlikely(atomic_long_sub_return_release(RWSEM_ACTIVE_WRITE_BIAS,
(atomic_long_t *)&sem->count) < 0))
rwsem_wake(sem);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| richard kuo | richard kuo | 37 | 97.37% | 1 | 50.00% |
| davidlohr bueso | davidlohr bueso | 1 | 2.63% | 1 | 50.00% |
| Total | 38 | 100.00% | 2 | 100.00% |
/*
* implement atomic add functionality
*/
static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem)
{
atomic_long_add(delta, (atomic_long_t *)&sem->count);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| richard kuo | richard kuo | 29 | 100.00% | 1 | 100.00% |
| Total | 29 | 100.00% | 1 | 100.00% |
/*
* downgrade write lock to read lock
*/
static inline void __downgrade_write(struct rw_semaphore *sem)
{
long tmp;
/*
* When downgrading from exclusive to shared ownership,
* anything inside the write-locked region cannot leak
* into the read side. In contrast, anything in the
* read-locked region is ok to be re-ordered into the
* write side. As such, rely on RELEASE semantics.
*/
tmp = atomic_long_add_return_release(-RWSEM_WAITING_BIAS,
(atomic_long_t *)&sem->count);
if (tmp < 0)
rwsem_downgrade_wake(sem);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| richard kuo | richard kuo | 42 | 95.45% | 1 | 50.00% |
| davidlohr bueso | davidlohr bueso | 2 | 4.55% | 1 | 50.00% |
| Total | 44 | 100.00% | 2 | 100.00% |
/*
* implement exchange and add functionality
*/
static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
{
return atomic_long_add_return(delta, (atomic_long_t *)&sem->count);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| richard kuo | richard kuo | 30 | 100.00% | 1 | 100.00% |
| Total | 30 | 100.00% | 1 | 100.00% |
#endif /* __KERNEL__ */
#endif /* _ASM_GENERIC_RWSEM_H */
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| richard kuo | richard kuo | 416 | 85.42% | 1 | 20.00% |
| michal hocko | michal hocko | 58 | 11.91% | 2 | 40.00% |
| davidlohr bueso | davidlohr bueso | 8 | 1.64% | 1 | 20.00% |
| will deacon | will deacon | 5 | 1.03% | 1 | 20.00% |
| Total | 487 | 100.00% | 5 | 100.00% |
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