318 lines
6.9 KiB
C
318 lines
6.9 KiB
C
#ifndef _ASM_X86_ATOMIC_H
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#define _ASM_X86_ATOMIC_H
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <asm/processor.h>
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#include <asm/alternative.h>
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#include <asm/cmpxchg.h>
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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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static inline int atomic_read(const atomic_t *v)
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{
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return (*(volatile int *)&(v)->counter);
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}
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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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static inline void atomic_set(atomic_t *v, int i)
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{
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v->counter = i;
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}
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/**
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* atomic_add - add integer to atomic variable
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* @i: integer value to add
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* @v: pointer of type atomic_t
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*
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* Atomically adds @i to @v.
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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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asm volatile(LOCK_PREFIX "addl %1,%0"
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: "+m" (v->counter)
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: "ir" (i));
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}
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/**
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* atomic_sub - subtract integer from atomic variable
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* @i: integer value to subtract
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* @v: pointer of type atomic_t
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*
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* Atomically subtracts @i from @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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asm volatile(LOCK_PREFIX "subl %1,%0"
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: "+m" (v->counter)
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: "ir" (i));
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}
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/**
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* atomic_sub_and_test - subtract value from variable and test result
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* @i: integer value to subtract
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* @v: pointer of type atomic_t
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*
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* Atomically subtracts @i from @v and returns
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* true if the result is zero, or false for all
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* other cases.
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*/
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static inline int atomic_sub_and_test(int i, atomic_t *v)
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{
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unsigned char c;
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asm volatile(LOCK_PREFIX "subl %2,%0; sete %1"
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: "+m" (v->counter), "=qm" (c)
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: "ir" (i) : "memory");
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return c;
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}
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/**
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* atomic_inc - increment atomic variable
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* @v: pointer of type atomic_t
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*
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* Atomically increments @v by 1.
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*/
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static inline void atomic_inc(atomic_t *v)
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{
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asm volatile(LOCK_PREFIX "incl %0"
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: "+m" (v->counter));
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}
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/**
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* atomic_dec - decrement atomic variable
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* @v: pointer of type atomic_t
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*
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* Atomically decrements @v by 1.
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*/
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static inline void atomic_dec(atomic_t *v)
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{
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asm volatile(LOCK_PREFIX "decl %0"
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: "+m" (v->counter));
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}
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/**
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* atomic_dec_and_test - decrement and test
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* @v: pointer of type atomic_t
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*
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* Atomically decrements @v by 1 and
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* returns true if the result is 0, or false for all other
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* cases.
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*/
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static inline int atomic_dec_and_test(atomic_t *v)
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{
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unsigned char c;
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asm volatile(LOCK_PREFIX "decl %0; sete %1"
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: "+m" (v->counter), "=qm" (c)
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: : "memory");
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return c != 0;
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}
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/**
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* atomic_inc_and_test - increment and test
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* @v: pointer of type atomic_t
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*
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* Atomically increments @v by 1
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* and returns true if the result is zero, or false for all
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* other cases.
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*/
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static inline int atomic_inc_and_test(atomic_t *v)
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{
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unsigned char c;
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asm volatile(LOCK_PREFIX "incl %0; sete %1"
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: "+m" (v->counter), "=qm" (c)
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: : "memory");
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return c != 0;
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}
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/**
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* atomic_add_negative - add and test if negative
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* @i: integer value to add
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* @v: pointer of type atomic_t
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*
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* Atomically adds @i to @v and returns true
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* if the result is negative, or false when
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* result is greater than or equal to zero.
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*/
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static inline int atomic_add_negative(int i, atomic_t *v)
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{
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unsigned char c;
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asm volatile(LOCK_PREFIX "addl %2,%0; sets %1"
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: "+m" (v->counter), "=qm" (c)
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: "ir" (i) : "memory");
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return c;
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}
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/**
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* atomic_add_return - add integer and return
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* @i: integer value to add
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* @v: pointer of type atomic_t
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*
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* Atomically adds @i to @v and returns @i + @v
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*/
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static inline int atomic_add_return(int i, atomic_t *v)
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{
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#ifdef CONFIG_M386
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int __i;
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unsigned long flags;
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if (unlikely(boot_cpu_data.x86 <= 3))
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goto no_xadd;
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#endif
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/* Modern 486+ processor */
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return i + xadd(&v->counter, i);
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#ifdef CONFIG_M386
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no_xadd: /* Legacy 386 processor */
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raw_local_irq_save(flags);
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__i = atomic_read(v);
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atomic_set(v, i + __i);
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raw_local_irq_restore(flags);
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return i + __i;
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#endif
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}
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/**
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* atomic_sub_return - subtract integer and return
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* @v: pointer of type atomic_t
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* @i: integer value to subtract
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*
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* Atomically subtracts @i from @v and returns @v - @i
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*/
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static inline int atomic_sub_return(int i, atomic_t *v)
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{
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return atomic_add_return(-i, v);
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}
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#define atomic_inc_return(v) (atomic_add_return(1, v))
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#define atomic_dec_return(v) (atomic_sub_return(1, v))
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static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
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{
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return cmpxchg(&v->counter, old, new);
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}
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static inline int atomic_xchg(atomic_t *v, int new)
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{
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return xchg(&v->counter, new);
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}
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/**
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* __atomic_add_unless - add unless the number is already a given value
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* @v: pointer of type atomic_t
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* @a: the amount to add to v...
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* @u: ...unless v is equal to u.
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*
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* Atomically adds @a to @v, so long as @v was not already @u.
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* Returns the old value of @v.
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*/
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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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for (;;) {
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if (unlikely(c == (u)))
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break;
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old = atomic_cmpxchg((v), c, c + (a));
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if (likely(old == c))
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break;
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c = old;
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}
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return c;
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}
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/*
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* atomic_dec_if_positive - decrement by 1 if old value positive
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* @v: pointer of type atomic_t
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*
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* The function returns the old value of *v minus 1, even if
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* the atomic variable, v, was not decremented.
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*/
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static inline int atomic_dec_if_positive(atomic_t *v)
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{
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int c, old, dec;
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c = atomic_read(v);
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for (;;) {
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dec = c - 1;
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if (unlikely(dec < 0))
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break;
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old = atomic_cmpxchg((v), c, dec);
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if (likely(old == c))
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break;
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c = old;
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}
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return dec;
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}
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/**
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* atomic_inc_short - increment of a short integer
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* @v: pointer to type int
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*
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* Atomically adds 1 to @v
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* Returns the new value of @u
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*/
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static inline short int atomic_inc_short(short int *v)
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{
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asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
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return *v;
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}
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#ifdef CONFIG_X86_64
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/**
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* atomic_or_long - OR of two long integers
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* @v1: pointer to type unsigned long
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* @v2: pointer to type unsigned long
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*
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* Atomically ORs @v1 and @v2
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* Returns the result of the OR
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*/
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static inline void atomic_or_long(unsigned long *v1, unsigned long v2)
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{
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asm(LOCK_PREFIX "orq %1, %0" : "+m" (*v1) : "r" (v2));
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}
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#endif
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/* These are x86-specific, used by some header files */
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#define atomic_clear_mask(mask, addr) \
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asm volatile(LOCK_PREFIX "andl %0,%1" \
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: : "r" (~(mask)), "m" (*(addr)) : "memory")
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#define atomic_set_mask(mask, addr) \
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asm volatile(LOCK_PREFIX "orl %0,%1" \
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: : "r" ((unsigned)(mask)), "m" (*(addr)) \
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: "memory")
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/* Atomic operations are already serializing on x86 */
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#define smp_mb__before_atomic_dec() barrier()
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#define smp_mb__after_atomic_dec() barrier()
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#define smp_mb__before_atomic_inc() barrier()
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#define smp_mb__after_atomic_inc() barrier()
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#ifdef CONFIG_X86_32
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# include "atomic64_32.h"
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#else
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# include "atomic64_64.h"
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#endif
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#endif /* _ASM_X86_ATOMIC_H */
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