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Diffstat (limited to 'include/asm-generic/atomic.h')
| -rw-r--r-- | include/asm-generic/atomic.h | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h new file mode 100644 index 000000000..11f96f40f --- /dev/null +++ b/include/asm-generic/atomic.h @@ -0,0 +1,196 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Generic C implementation of atomic counter operations. Usable on + * UP systems only. Do not include in machine independent code. + * + * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ +#ifndef __ASM_GENERIC_ATOMIC_H +#define __ASM_GENERIC_ATOMIC_H + +#include <asm/cmpxchg.h> +#include <asm/barrier.h> + +/* + * atomic_$op() - $op integer to atomic variable + * @i: integer value to $op + * @v: pointer to the atomic variable + * + * Atomically $ops @i to @v. Does not strictly guarantee a memory-barrier, use + * smp_mb__{before,after}_atomic(). + */ + +/* + * atomic_$op_return() - $op interer to atomic variable and returns the result + * @i: integer value to $op + * @v: pointer to the atomic variable + * + * Atomically $ops @i to @v. Does imply a full memory barrier. + */ + +#ifdef CONFIG_SMP + +/* we can build all atomic primitives from cmpxchg */ + +#define ATOMIC_OP(op, c_op) \ +static inline void atomic_##op(int i, atomic_t *v) \ +{ \ + int c, old; \ + \ + c = v->counter; \ + while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ + c = old; \ +} + +#define ATOMIC_OP_RETURN(op, c_op) \ +static inline int atomic_##op##_return(int i, atomic_t *v) \ +{ \ + int c, old; \ + \ + c = v->counter; \ + while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ + c = old; \ + \ + return c c_op i; \ +} + +#define ATOMIC_FETCH_OP(op, c_op) \ +static inline int atomic_fetch_##op(int i, atomic_t *v) \ +{ \ + int c, old; \ + \ + c = v->counter; \ + while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ + c = old; \ + \ + return c; \ +} + +#else + +#include <linux/irqflags.h> + +#define ATOMIC_OP(op, c_op) \ +static inline void atomic_##op(int i, atomic_t *v) \ +{ \ + unsigned long flags; \ + \ + raw_local_irq_save(flags); \ + v->counter = v->counter c_op i; \ + raw_local_irq_restore(flags); \ +} + +#define ATOMIC_OP_RETURN(op, c_op) \ +static inline int atomic_##op##_return(int i, atomic_t *v) \ +{ \ + unsigned long flags; \ + int ret; \ + \ + raw_local_irq_save(flags); \ + ret = (v->counter = v->counter c_op i); \ + raw_local_irq_restore(flags); \ + \ + return ret; \ +} + +#define ATOMIC_FETCH_OP(op, c_op) \ +static inline int atomic_fetch_##op(int i, atomic_t *v) \ +{ \ + unsigned long flags; \ + int ret; \ + \ + raw_local_irq_save(flags); \ + ret = v->counter; \ + v->counter = v->counter c_op i; \ + raw_local_irq_restore(flags); \ + \ + return ret; \ +} + +#endif /* CONFIG_SMP */ + +#ifndef atomic_add_return +ATOMIC_OP_RETURN(add, +) +#endif + +#ifndef atomic_sub_return +ATOMIC_OP_RETURN(sub, -) +#endif + +#ifndef atomic_fetch_add +ATOMIC_FETCH_OP(add, +) +#endif + +#ifndef atomic_fetch_sub +ATOMIC_FETCH_OP(sub, -) +#endif + +#ifndef atomic_fetch_and +ATOMIC_FETCH_OP(and, &) +#endif + +#ifndef atomic_fetch_or +ATOMIC_FETCH_OP(or, |) +#endif + +#ifndef atomic_fetch_xor +ATOMIC_FETCH_OP(xor, ^) +#endif + +#ifndef atomic_and +ATOMIC_OP(and, &) +#endif + +#ifndef atomic_or +ATOMIC_OP(or, |) +#endif + +#ifndef atomic_xor +ATOMIC_OP(xor, ^) +#endif + +#undef ATOMIC_FETCH_OP +#undef ATOMIC_OP_RETURN +#undef ATOMIC_OP + +/* + * Atomic operations that C can't guarantee us. Useful for + * resource counting etc.. + */ + +/** + * atomic_read - read atomic variable + * @v: pointer of type atomic_t + * + * Atomically reads the value of @v. + */ +#ifndef atomic_read +#define atomic_read(v) READ_ONCE((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) WRITE_ONCE(((v)->counter), (i)) + +#include <linux/irqflags.h> + +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); +} + +#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) +#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) + +#endif /* __ASM_GENERIC_ATOMIC_H */ |