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188 lines
4.2 KiB
188 lines
4.2 KiB
/* |
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* Generic C implementation of atomic counter operations. Usable on |
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* UP systems only. Do not include in machine independent code. |
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* |
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* Originally implemented for MN10300. |
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* |
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. |
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* Written by David Howells (dhowells@redhat.com) |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public Licence |
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* as published by the Free Software Foundation; either version |
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* 2 of the Licence, or (at your option) any later version. |
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*/ |
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#ifndef __ASM_GENERIC_ATOMIC_H |
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#define __ASM_GENERIC_ATOMIC_H |
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#include <asm/cmpxchg.h> |
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#include <asm/barrier.h> |
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/* |
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* atomic_$op() - $op integer to atomic variable |
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* @i: integer value to $op |
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* @v: pointer to the atomic variable |
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* |
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* Atomically $ops @i to @v. Does not strictly guarantee a memory-barrier, use |
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* smp_mb__{before,after}_atomic(). |
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*/ |
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/* |
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* atomic_$op_return() - $op interer to atomic variable and returns the result |
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* @i: integer value to $op |
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* @v: pointer to the atomic variable |
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* |
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* Atomically $ops @i to @v. Does imply a full memory barrier. |
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*/ |
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#ifdef CONFIG_SMP |
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/* we can build all atomic primitives from cmpxchg */ |
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#define ATOMIC_OP(op, c_op) \ |
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static inline void atomic_##op(int i, atomic_t *v) \ |
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{ \ |
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int c, old; \ |
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\ |
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c = v->counter; \ |
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while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ |
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c = old; \ |
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} |
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#define ATOMIC_OP_RETURN(op, c_op) \ |
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static inline int atomic_##op##_return(int i, atomic_t *v) \ |
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{ \ |
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int c, old; \ |
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\ |
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c = v->counter; \ |
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while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ |
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c = old; \ |
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\ |
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return c c_op i; \ |
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} |
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#else |
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#include <linux/irqflags.h> |
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#define ATOMIC_OP(op, c_op) \ |
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static inline void atomic_##op(int i, atomic_t *v) \ |
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{ \ |
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unsigned long flags; \ |
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\ |
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raw_local_irq_save(flags); \ |
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v->counter = v->counter c_op i; \ |
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raw_local_irq_restore(flags); \ |
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} |
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#define ATOMIC_OP_RETURN(op, c_op) \ |
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static inline int atomic_##op##_return(int i, atomic_t *v) \ |
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{ \ |
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unsigned long flags; \ |
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int ret; \ |
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\ |
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raw_local_irq_save(flags); \ |
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ret = (v->counter = v->counter c_op i); \ |
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raw_local_irq_restore(flags); \ |
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\ |
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return ret; \ |
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} |
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#endif /* CONFIG_SMP */ |
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#ifndef atomic_add_return |
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ATOMIC_OP_RETURN(add, +) |
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#endif |
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#ifndef atomic_sub_return |
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ATOMIC_OP_RETURN(sub, -) |
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#endif |
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#ifndef atomic_and |
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ATOMIC_OP(and, &) |
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#endif |
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#ifndef atomic_or |
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ATOMIC_OP(or, |) |
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#endif |
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#ifndef atomic_xor |
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ATOMIC_OP(xor, ^) |
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#endif |
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#undef ATOMIC_OP_RETURN |
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#undef ATOMIC_OP |
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/* |
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* Atomic operations that C can't guarantee us. Useful for |
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* resource counting etc.. |
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*/ |
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#define ATOMIC_INIT(i) { (i) } |
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/** |
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* atomic_read - read atomic variable |
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* @v: pointer of type atomic_t |
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* |
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* Atomically reads the value of @v. |
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*/ |
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#ifndef atomic_read |
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#define atomic_read(v) READ_ONCE((v)->counter) |
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#endif |
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/** |
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* atomic_set - set atomic variable |
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* @v: pointer of type atomic_t |
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* @i: required value |
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* |
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* Atomically sets the value of @v to @i. |
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*/ |
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#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i)) |
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#include <linux/irqflags.h> |
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static inline int atomic_add_negative(int i, atomic_t *v) |
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{ |
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return atomic_add_return(i, v) < 0; |
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} |
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static inline void atomic_add(int i, atomic_t *v) |
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{ |
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atomic_add_return(i, v); |
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} |
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static inline void atomic_sub(int i, atomic_t *v) |
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{ |
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atomic_sub_return(i, v); |
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} |
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static inline void atomic_inc(atomic_t *v) |
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{ |
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atomic_add_return(1, v); |
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} |
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static inline void atomic_dec(atomic_t *v) |
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{ |
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atomic_sub_return(1, v); |
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} |
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#define atomic_dec_return(v) atomic_sub_return(1, (v)) |
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#define atomic_inc_return(v) atomic_add_return(1, (v)) |
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#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0) |
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#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0) |
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#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0) |
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#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) |
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#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) |
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static inline int __atomic_add_unless(atomic_t *v, int a, int u) |
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{ |
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int c, old; |
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c = atomic_read(v); |
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while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c) |
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c = old; |
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return c; |
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} |
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#endif /* __ASM_GENERIC_ATOMIC_H */
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