linux/arch/xtensa/include/asm/rwsem.h
Thomas Gleixner aac72277fd rwsem: Move duplicate function prototypes to linux/rwsem.h
All architecture specific rwsem headers carry the same function
prototypes. Just x86 adds asmregparm, which is an empty define on all
other architectures. S390 has a stale rwsem_downgrade_write()
prototype.

Remove the duplicates and add the prototypes to linux/rwsem.h

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Richard Henderson <rth@twiddle.net>
Acked-by: Tony Luck <tony.luck@intel.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Acked-by: David Miller <davem@davemloft.net>
Cc: Chris Zankel <chris@zankel.net>
LKML-Reference: <20110126195833.970840140@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-01-27 12:30:39 +01:00

131 lines
2.7 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
#ifndef _LINUX_RWSEM_H
#error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead."
#endif
#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)
/*
* 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));
}
#endif /* _XTENSA_RWSEM_H */