aac72277fd
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>
132 lines
2.6 KiB
C
132 lines
2.6 KiB
C
/*
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* include/asm-sh/rwsem.h: R/W semaphores for SH using the stuff
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* in lib/rwsem.c.
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*/
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#ifndef _ASM_SH_RWSEM_H
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#define _ASM_SH_RWSEM_H
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#ifndef _LINUX_RWSEM_H
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#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
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#endif
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#ifdef __KERNEL__
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#define RWSEM_UNLOCKED_VALUE 0x00000000
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#define RWSEM_ACTIVE_BIAS 0x00000001
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#define RWSEM_ACTIVE_MASK 0x0000ffff
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#define RWSEM_WAITING_BIAS (-0x00010000)
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#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
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#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
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/*
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* lock for reading
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*/
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static inline void __down_read(struct rw_semaphore *sem)
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{
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if (atomic_inc_return((atomic_t *)(&sem->count)) > 0)
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smp_wmb();
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else
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rwsem_down_read_failed(sem);
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}
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static inline int __down_read_trylock(struct rw_semaphore *sem)
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{
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int tmp;
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while ((tmp = sem->count) >= 0) {
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if (tmp == cmpxchg(&sem->count, tmp,
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tmp + RWSEM_ACTIVE_READ_BIAS)) {
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smp_wmb();
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return 1;
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}
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}
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return 0;
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}
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/*
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* lock for writing
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*/
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static inline void __down_write(struct rw_semaphore *sem)
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{
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int tmp;
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tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
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(atomic_t *)(&sem->count));
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if (tmp == RWSEM_ACTIVE_WRITE_BIAS)
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smp_wmb();
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else
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rwsem_down_write_failed(sem);
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}
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static inline int __down_write_trylock(struct rw_semaphore *sem)
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{
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int tmp;
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tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
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RWSEM_ACTIVE_WRITE_BIAS);
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smp_wmb();
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return tmp == RWSEM_UNLOCKED_VALUE;
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}
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/*
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* unlock after reading
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*/
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static inline void __up_read(struct rw_semaphore *sem)
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{
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int tmp;
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smp_wmb();
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tmp = atomic_dec_return((atomic_t *)(&sem->count));
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if (tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)
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rwsem_wake(sem);
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}
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/*
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* unlock after writing
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*/
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static inline void __up_write(struct rw_semaphore *sem)
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{
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smp_wmb();
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if (atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
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(atomic_t *)(&sem->count)) < 0)
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rwsem_wake(sem);
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}
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/*
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* implement atomic add functionality
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*/
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static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
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{
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atomic_add(delta, (atomic_t *)(&sem->count));
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}
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/*
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* downgrade write lock to read lock
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*/
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static inline void __downgrade_write(struct rw_semaphore *sem)
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{
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int tmp;
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smp_wmb();
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tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
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if (tmp < 0)
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rwsem_downgrade_wake(sem);
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}
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static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
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{
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__down_write(sem);
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}
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/*
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* implement exchange and add functionality
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*/
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static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
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{
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smp_mb();
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return atomic_add_return(delta, (atomic_t *)(&sem->count));
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}
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#endif /* __KERNEL__ */
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#endif /* _ASM_SH_RWSEM_H */
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