/* * Generic C implementation of atomic counter operations. Usable on * UP systems only. Do not include in machine independent code. * * Originally implemented for MN10300. * * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. */#ifndef __ASM_GENERIC_ATOMIC_H#define __ASM_GENERIC_ATOMIC_H #include <asm/cmpxchg.h> #ifdef CONFIG_SMP/* Force people to define core atomics */# if !defined(atomic_add_return) || !defined(atomic_sub_return) || \     !defined(atomic_clear_mask) || !defined(atomic_set_mask)#  error "SMP requires a little arch-specific magic"# endif#endif /* * Atomic operations that C can't guarantee us.  Useful for * resource counting etc.. */ #define ATOMIC_INIT(i)	{ (i) } #ifdef __KERNEL__ /** * atomic_read - read atomic variable * @v: pointer of type atomic_t * * Atomically reads the value of @v. */#ifndef atomic_read#define atomic_read(v)	(*(volatile int *)&(v)->counter)#endif /** * atomic_set - set atomic variable * @v: pointer of type atomic_t * @i: required value * * Atomically sets the value of @v to @i. */#define atomic_set(v, i) (((v)->counter) = (i)) #include <linux/irqflags.h> /** * atomic_add_return - add integer to atomic variable * @i: integer value to add * @v: pointer of type atomic_t * * Atomically adds @i to @v and returns the result */#ifndef atomic_add_returnstatic inline int atomic_add_return(int i, atomic_t *v){	unsigned long flags;	int temp; 	raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */	temp = v->counter;	temp += i;	v->counter = temp;	raw_local_irq_restore(flags); 	return temp;}#endif /** * atomic_sub_return - subtract integer from atomic variable * @i: integer value to subtract * @v: pointer of type atomic_t * * Atomically subtracts @i from @v and returns the result */#ifndef atomic_sub_returnstatic inline int atomic_sub_return(int i, atomic_t *v){	unsigned long flags;	int temp; 	raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */	temp = v->counter;	temp -= i;	v->counter = temp;	raw_local_irq_restore(flags); 	return temp;}#endif static inline int atomic_add_negative(int i, atomic_t *v){	return atomic_add_return(i, v) < 0;} static inline void atomic_add(int i, atomic_t *v){	atomic_add_return(i, v);} static inline void atomic_sub(int i, atomic_t *v){	atomic_sub_return(i, v);} static inline void atomic_inc(atomic_t *v){	atomic_add_return(1, v);} static inline void atomic_dec(atomic_t *v){	atomic_sub_return(1, v);} #define atomic_dec_return(v)		atomic_sub_return(1, (v))#define atomic_inc_return(v)		atomic_add_return(1, (v)) #define atomic_sub_and_test(i, v)	(atomic_sub_return((i), (v)) == 0)#define atomic_dec_and_test(v)		(atomic_dec_return(v) == 0)#define atomic_inc_and_test(v)		(atomic_inc_return(v) == 0) #define atomic_xchg(ptr, v)		(xchg(&(ptr)->counter, (v)))#define atomic_cmpxchg(v, old, new)	(cmpxchg(&((v)->counter), (old), (new))) static inline int __atomic_add_unless(atomic_t *v, int a, int u){  int c, old;  c = atomic_read(v);  while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)    c = old;  return c;} /** * atomic_clear_mask - Atomically clear bits in atomic variable * @mask: Mask of the bits to be cleared * @v: pointer of type atomic_t * * Atomically clears the bits set in @mask from @v */#ifndef atomic_clear_maskstatic inline void atomic_clear_mask(unsigned long mask, atomic_t *v){	unsigned long flags; 	mask = ~mask;	raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */	v->counter &= mask;	raw_local_irq_restore(flags);}#endif /** * atomic_set_mask - Atomically set bits in atomic variable * @mask: Mask of the bits to be set * @v: pointer of type atomic_t * * Atomically sets the bits set in @mask in @v */#ifndef atomic_set_maskstatic inline void atomic_set_mask(unsigned int mask, atomic_t *v){	unsigned long flags; 	raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */	v->counter |= mask;	raw_local_irq_restore(flags);}#endif /* Assume that atomic operations are already serializing */#define smp_mb__before_atomic_dec()	barrier()#define smp_mb__after_atomic_dec()	barrier()#define smp_mb__before_atomic_inc()	barrier()#define smp_mb__after_atomic_inc()	barrier() #endif /* __KERNEL__ */#endif /* __ASM_GENERIC_ATOMIC_H */