2005-04-16 18:20:36 -04:00
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#ifndef __ARCH_I386_ATOMIC__
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#define __ARCH_I386_ATOMIC__
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#include <linux/compiler.h>
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#include <asm/processor.h>
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2007-05-08 03:35:02 -04:00
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#include <asm/cmpxchg.h>
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2005-04-16 18:20:36 -04:00
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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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/*
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* Make sure gcc doesn't try to be clever and move things around
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* on us. We need to use _exactly_ the address the user gave us,
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* not some alias that contains the same information.
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*/
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2008-03-23 04:01:41 -04:00
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typedef struct {
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int counter;
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} atomic_t;
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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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#define atomic_read(v) ((v)->counter)
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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) (((v)->counter) = (i))
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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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2008-03-23 04:01:41 -04:00
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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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2008-03-23 04:01:41 -04:00
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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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* @v: pointer of type atomic_t
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* @i: integer value to add
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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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2008-03-23 04:01:41 -04:00
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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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2007-05-08 03:35:08 -04:00
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* atomic_add_return - add integer and return
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* @v: pointer of type atomic_t
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* @i: integer value to add
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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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int __i;
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#ifdef CONFIG_M386
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2006-04-19 01:21:10 -04:00
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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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__i = i;
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asm volatile(LOCK_PREFIX "xaddl %0, %1"
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: "+r" (i), "+m" (v->counter)
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: : "memory");
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return i + __i;
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#ifdef CONFIG_M386
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no_xadd: /* Legacy 386 processor */
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2006-04-19 01:21:10 -04:00
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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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2006-04-19 01:21:10 -04:00
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local_irq_restore(flags);
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2005-04-16 18:20:36 -04:00
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return i + __i;
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#endif
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}
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2007-05-08 03:35:08 -04:00
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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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2007-05-08 03:34:20 -04:00
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#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
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#define atomic_xchg(v, new) (xchg(&((v)->counter), (new)))
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2005-11-13 19:07:24 -05:00
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2005-11-13 19:07:25 -05:00
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/**
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2007-02-10 04:45:59 -05:00
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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 non-zero if @v was not @u, and zero otherwise.
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*/
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2008-03-23 04:01:41 -04:00
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static inline int atomic_add_unless(atomic_t *v, int a, int u)
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2007-05-08 03:34:38 -04:00
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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 != (u);
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}
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2005-11-13 19:07:25 -05:00
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#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
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2008-03-23 04:01:41 -04:00
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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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/* 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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2008-03-23 04:01:41 -04:00
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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" (mask), "m" (*(addr)) : "memory")
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2005-04-16 18:20:36 -04:00
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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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2006-01-06 03:11:20 -05:00
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#include <asm-generic/atomic.h>
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#endif
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