mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-05 19:46:40 +07:00
61f4c3d6db
RWSEM_DEBUG used to be a printk based 'tracing' facility, probably used for very early prototypes of the rwsem code. Remove it. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
165 lines
3.6 KiB
C
165 lines
3.6 KiB
C
/*
|
|
* include/asm-xtensa/rwsem.h
|
|
*
|
|
* This file is subject to the terms and conditions of the GNU General Public
|
|
* License. See the file "COPYING" in the main directory of this archive
|
|
* for more details.
|
|
*
|
|
* Largely copied from include/asm-ppc/rwsem.h
|
|
*
|
|
* Copyright (C) 2001 - 2005 Tensilica Inc.
|
|
*/
|
|
|
|
#ifndef _XTENSA_RWSEM_H
|
|
#define _XTENSA_RWSEM_H
|
|
|
|
#include <linux/list.h>
|
|
#include <linux/spinlock.h>
|
|
#include <asm/atomic.h>
|
|
#include <asm/system.h>
|
|
|
|
/*
|
|
* the semaphore definition
|
|
*/
|
|
struct rw_semaphore {
|
|
signed 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;
|
|
};
|
|
|
|
#define __RWSEM_INITIALIZER(name) \
|
|
{ RWSEM_UNLOCKED_VALUE, SPIN_LOCK_UNLOCKED, \
|
|
LIST_HEAD_INIT((name).wait_list) }
|
|
|
|
#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);
|
|
}
|
|
|
|
/*
|
|
* lock for reading
|
|
*/
|
|
static inline void __down_read(struct rw_semaphore *sem)
|
|
{
|
|
if (atomic_add_return(1,(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_sub_return(1,(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);
|
|
}
|
|
|
|
/*
|
|
* 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 /* _XTENSA_RWSEM_H */
|