]>
git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - include/asm-generic/atomic.h
2 * Generic C implementation of atomic counter operations. Usable on
3 * UP systems only. Do not include in machine independent code.
5 * Originally implemented for MN10300.
7 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
8 * Written by David Howells (dhowells@redhat.com)
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public Licence
12 * as published by the Free Software Foundation; either version
13 * 2 of the Licence, or (at your option) any later version.
15 #ifndef __ASM_GENERIC_ATOMIC_H
16 #define __ASM_GENERIC_ATOMIC_H
23 * Atomic operations that C can't guarantee us. Useful for
24 * resource counting etc..
27 #define ATOMIC_INIT(i) { (i) }
32 * atomic_read - read atomic variable
33 * @v: pointer of type atomic_t
35 * Atomically reads the value of @v.
37 #define atomic_read(v) (*(volatile int *)&(v)->counter)
40 * atomic_set - set atomic variable
41 * @v: pointer of type atomic_t
44 * Atomically sets the value of @v to @i.
46 #define atomic_set(v, i) (((v)->counter) = (i))
48 #include <linux/irqflags.h>
49 #include <asm/system.h>
52 * atomic_add_return - add integer to atomic variable
53 * @i: integer value to add
54 * @v: pointer of type atomic_t
56 * Atomically adds @i to @v and returns the result
58 static inline int atomic_add_return(int i
, atomic_t
*v
)
63 raw_local_irq_save(flags
); /* Don't trace it in an irqsoff handler */
67 raw_local_irq_restore(flags
);
73 * atomic_sub_return - subtract integer from atomic variable
74 * @i: integer value to subtract
75 * @v: pointer of type atomic_t
77 * Atomically subtracts @i from @v and returns the result
79 static inline int atomic_sub_return(int i
, atomic_t
*v
)
84 raw_local_irq_save(flags
); /* Don't trace it in an irqsoff handler */
88 raw_local_irq_restore(flags
);
93 static inline int atomic_add_negative(int i
, atomic_t
*v
)
95 return atomic_add_return(i
, v
) < 0;
98 static inline void atomic_add(int i
, atomic_t
*v
)
100 atomic_add_return(i
, v
);
103 static inline void atomic_sub(int i
, atomic_t
*v
)
105 atomic_sub_return(i
, v
);
108 static inline void atomic_inc(atomic_t
*v
)
110 atomic_add_return(1, v
);
113 static inline void atomic_dec(atomic_t
*v
)
115 atomic_sub_return(1, v
);
118 #define atomic_dec_return(v) atomic_sub_return(1, (v))
119 #define atomic_inc_return(v) atomic_add_return(1, (v))
121 #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
122 #define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
123 #define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
125 #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
126 #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
128 #define cmpxchg_local(ptr, o, n) \
129 ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
130 (unsigned long)(n), sizeof(*(ptr))))
132 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
134 static inline int __atomic_add_unless(atomic_t
*v
, int a
, int u
)
138 while (c
!= u
&& (old
= atomic_cmpxchg(v
, c
, c
+ a
)) != c
)
143 static inline void atomic_clear_mask(unsigned long mask
, unsigned long *addr
)
148 raw_local_irq_save(flags
); /* Don't trace it in a irqsoff handler */
150 raw_local_irq_restore(flags
);
153 /* Assume that atomic operations are already serializing */
154 #define smp_mb__before_atomic_dec() barrier()
155 #define smp_mb__after_atomic_dec() barrier()
156 #define smp_mb__before_atomic_inc() barrier()
157 #define smp_mb__after_atomic_inc() barrier()
159 #endif /* __KERNEL__ */
160 #endif /* __ASM_GENERIC_ATOMIC_H */