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/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef ARCH_SMP_ATOMIC_H
#define ARCH_SMP_ATOMIC_H
/*
* Make sure gcc doesn't try to be clever and move things around
* on us. We need to use _exactly_ the address the user gave us,
* not some alias that contains the same information.
*/
typedef struct { volatile int counter; } atomic_t;
#define ATOMIC_INIT(i) { (i) }
/** @file x86/include/arch/smp/atomic.h
*
* Atomic operations that C can't guarantee us. Useful for
* resource counting etc..
*/
/**
* atomic_read - read atomic variable
* @param v: pointer of type atomic_t
*
* Atomically reads the value of v. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
#define atomic_read(v) ((v)->counter)
/**
* atomic_set - set atomic variable
* @param v: pointer of type atomic_t
* @param i: required value
*
* Atomically sets the value of v to i. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
#define atomic_set(v, i) (((v)->counter) = (i))
/**
* atomic_inc - increment atomic variable
* @param v: pointer of type atomic_t
*
* Atomically increments v by 1. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
static __always_inline void atomic_inc(atomic_t *v)
{
__asm__ __volatile__(
"lock ; incl %0"
: "=m" (v->counter)
: "m" (v->counter));
}
/**
* atomic_dec - decrement atomic variable
* @param v: pointer of type atomic_t
*
* Atomically decrements v by 1. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
static __always_inline void atomic_dec(atomic_t *v)
{
__asm__ __volatile__(
"lock ; decl %0"
: "=m" (v->counter)
: "m" (v->counter));
}
#endif /* ARCH_SMP_ATOMIC_H */
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