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ed4aad50ea
We've been using an atomic_t implementation subset based on the gcc builtin functions for a while, now, with refcount.h we need cmpxchg(), use gcc's __sync_val_compare_and_swap() for that. Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Elena Reshetova <elena.reshetova@intel.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/n/tip-b9zovyxgpa0c4vi3nm0kjo97@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
71 lines
1.5 KiB
C
71 lines
1.5 KiB
C
#ifndef __TOOLS_ASM_GENERIC_ATOMIC_H
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#define __TOOLS_ASM_GENERIC_ATOMIC_H
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#include <linux/compiler.h>
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#include <linux/types.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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* Excerpts obtained from the Linux kernel sources.
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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 ACCESS_ONCE((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_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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__sync_add_and_fetch(&v->counter, 1);
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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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return __sync_sub_and_fetch(&v->counter, 1) == 0;
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}
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#define cmpxchg(ptr, oldval, newval) \
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__sync_val_compare_and_swap(ptr, oldval, newval)
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static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
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{
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return cmpxchg(&(v)->counter, oldval, newval);
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}
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#endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */
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