819165fb34
Eric pointed out overly restrictive constraints in atomic64_set(), but there are issues throughout the file. In the cited case, %ebx and %ecx are inputs only (don't get changed by either of the two low level implementations). This was also the case elsewhere. Further in many cases early-clobber indicators were missing. Finally, the previous implementation rolled a custom alternative instruction macro from scratch, rather than using alternative_call() (which was introduced with the commit that the description of the change in question actually refers to). Adjusting has the benefit of not hiding referenced symbols from the compiler, which however requires them to be declared not just in the exporting source file (which, as a desirable side effect, in turn allows that exporting file to become a real 5-line stub). This patch does not eliminate the overly restrictive memory clobbers, however: Doing so would occasionally make the compiler set up a second register for accessing the memory object (to satisfy the added "m" constraint), and it's not clear which of the two non-optimal alternatives is better. v2: Re-do the declaration and exporting of the internal symbols. Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Jan Beulich <jbeulich@suse.com> Link: http://lkml.kernel.org/r/4F19A2A5020000780006E0D9@nat28.tlf.novell.com Cc: Luca Barbieri <luca@luca-barbieri.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
318 lines
7.5 KiB
C
318 lines
7.5 KiB
C
#ifndef _ASM_X86_ATOMIC64_32_H
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#define _ASM_X86_ATOMIC64_32_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/cmpxchg.h>
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/* An 64bit atomic type */
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typedef struct {
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u64 __aligned(8) counter;
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} atomic64_t;
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#define ATOMIC64_INIT(val) { (val) }
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#define __ATOMIC64_DECL(sym) void atomic64_##sym(atomic64_t *, ...)
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#ifndef ATOMIC64_EXPORT
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#define ATOMIC64_DECL_ONE __ATOMIC64_DECL
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#else
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#define ATOMIC64_DECL_ONE(sym) __ATOMIC64_DECL(sym); \
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ATOMIC64_EXPORT(atomic64_##sym)
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#endif
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#ifdef CONFIG_X86_CMPXCHG64
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#define __alternative_atomic64(f, g, out, in...) \
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asm volatile("call %P[func]" \
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: out : [func] "i" (atomic64_##g##_cx8), ## in)
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#define ATOMIC64_DECL(sym) ATOMIC64_DECL_ONE(sym##_cx8)
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#else
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#define __alternative_atomic64(f, g, out, in...) \
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alternative_call(atomic64_##f##_386, atomic64_##g##_cx8, \
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X86_FEATURE_CX8, ASM_OUTPUT2(out), ## in)
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#define ATOMIC64_DECL(sym) ATOMIC64_DECL_ONE(sym##_cx8); \
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ATOMIC64_DECL_ONE(sym##_386)
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ATOMIC64_DECL_ONE(add_386);
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ATOMIC64_DECL_ONE(sub_386);
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ATOMIC64_DECL_ONE(inc_386);
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ATOMIC64_DECL_ONE(dec_386);
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#endif
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#define alternative_atomic64(f, out, in...) \
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__alternative_atomic64(f, f, ASM_OUTPUT2(out), ## in)
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ATOMIC64_DECL(read);
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ATOMIC64_DECL(set);
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ATOMIC64_DECL(xchg);
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ATOMIC64_DECL(add_return);
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ATOMIC64_DECL(sub_return);
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ATOMIC64_DECL(inc_return);
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ATOMIC64_DECL(dec_return);
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ATOMIC64_DECL(dec_if_positive);
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ATOMIC64_DECL(inc_not_zero);
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ATOMIC64_DECL(add_unless);
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#undef ATOMIC64_DECL
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#undef ATOMIC64_DECL_ONE
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#undef __ATOMIC64_DECL
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#undef ATOMIC64_EXPORT
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/**
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* atomic64_cmpxchg - cmpxchg atomic64 variable
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* @p: pointer to type atomic64_t
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* @o: expected value
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* @n: new value
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*
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* Atomically sets @v to @n if it was equal to @o and returns
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* the old value.
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*/
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static inline long long atomic64_cmpxchg(atomic64_t *v, long long o, long long n)
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{
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return cmpxchg64(&v->counter, o, n);
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}
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/**
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* atomic64_xchg - xchg atomic64 variable
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* @v: pointer to type atomic64_t
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* @n: value to assign
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*
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* Atomically xchgs the value of @v to @n and returns
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* the old value.
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*/
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static inline long long atomic64_xchg(atomic64_t *v, long long n)
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{
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long long o;
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unsigned high = (unsigned)(n >> 32);
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unsigned low = (unsigned)n;
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alternative_atomic64(xchg, "=&A" (o),
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"S" (v), "b" (low), "c" (high)
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: "memory");
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return o;
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}
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/**
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* atomic64_set - set atomic64 variable
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* @v: pointer to type atomic64_t
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* @n: value to assign
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*
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* Atomically sets the value of @v to @n.
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*/
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static inline void atomic64_set(atomic64_t *v, long long i)
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{
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unsigned high = (unsigned)(i >> 32);
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unsigned low = (unsigned)i;
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alternative_atomic64(set, /* no output */,
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"S" (v), "b" (low), "c" (high)
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: "eax", "edx", "memory");
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}
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/**
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* atomic64_read - read atomic64 variable
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* @v: pointer to type atomic64_t
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*
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* Atomically reads the value of @v and returns it.
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*/
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static inline long long atomic64_read(const atomic64_t *v)
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{
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long long r;
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alternative_atomic64(read, "=&A" (r), "c" (v) : "memory");
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return r;
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}
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/**
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* atomic64_add_return - add and return
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* @i: integer value to add
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* @v: pointer to type atomic64_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 long long atomic64_add_return(long long i, atomic64_t *v)
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{
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alternative_atomic64(add_return,
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ASM_OUTPUT2("+A" (i), "+c" (v)),
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ASM_NO_INPUT_CLOBBER("memory"));
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return i;
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}
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/*
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* Other variants with different arithmetic operators:
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*/
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static inline long long atomic64_sub_return(long long i, atomic64_t *v)
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{
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alternative_atomic64(sub_return,
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ASM_OUTPUT2("+A" (i), "+c" (v)),
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ASM_NO_INPUT_CLOBBER("memory"));
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return i;
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}
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static inline long long atomic64_inc_return(atomic64_t *v)
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{
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long long a;
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alternative_atomic64(inc_return, "=&A" (a),
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"S" (v) : "memory", "ecx");
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return a;
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}
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static inline long long atomic64_dec_return(atomic64_t *v)
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{
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long long a;
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alternative_atomic64(dec_return, "=&A" (a),
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"S" (v) : "memory", "ecx");
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return a;
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}
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/**
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* atomic64_add - add integer to atomic64 variable
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* @i: integer value to add
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* @v: pointer to type atomic64_t
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*
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* Atomically adds @i to @v.
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*/
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static inline long long atomic64_add(long long i, atomic64_t *v)
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{
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__alternative_atomic64(add, add_return,
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ASM_OUTPUT2("+A" (i), "+c" (v)),
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ASM_NO_INPUT_CLOBBER("memory"));
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return i;
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}
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/**
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* atomic64_sub - subtract the atomic64 variable
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* @i: integer value to subtract
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* @v: pointer to type atomic64_t
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*
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* Atomically subtracts @i from @v.
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*/
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static inline long long atomic64_sub(long long i, atomic64_t *v)
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{
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__alternative_atomic64(sub, sub_return,
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ASM_OUTPUT2("+A" (i), "+c" (v)),
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ASM_NO_INPUT_CLOBBER("memory"));
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return i;
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}
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/**
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* atomic64_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 to type atomic64_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 atomic64_sub_and_test(long long i, atomic64_t *v)
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{
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return atomic64_sub_return(i, v) == 0;
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}
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/**
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* atomic64_inc - increment atomic64 variable
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* @v: pointer to type atomic64_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 atomic64_inc(atomic64_t *v)
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{
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__alternative_atomic64(inc, inc_return, /* no output */,
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"S" (v) : "memory", "eax", "ecx", "edx");
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}
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/**
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* atomic64_dec - decrement atomic64 variable
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* @ptr: pointer to type atomic64_t
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*
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* Atomically decrements @ptr by 1.
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*/
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static inline void atomic64_dec(atomic64_t *v)
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{
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__alternative_atomic64(dec, dec_return, /* no output */,
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"S" (v) : "memory", "eax", "ecx", "edx");
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}
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/**
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* atomic64_dec_and_test - decrement and test
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* @v: pointer to type atomic64_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 atomic64_dec_and_test(atomic64_t *v)
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{
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return atomic64_dec_return(v) == 0;
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}
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/**
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* atomic64_inc_and_test - increment and test
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* @v: pointer to type atomic64_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 atomic64_inc_and_test(atomic64_t *v)
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{
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return atomic64_inc_return(v) == 0;
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}
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/**
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* atomic64_add_negative - add and test if negative
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* @i: integer value to add
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* @v: pointer to type atomic64_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 atomic64_add_negative(long long i, atomic64_t *v)
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{
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return atomic64_add_return(i, v) < 0;
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}
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/**
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* atomic64_add_unless - add unless the number is a given value
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* @v: pointer of type atomic64_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 it was not @u.
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* Returns non-zero if the add was done, zero otherwise.
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*/
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static inline int atomic64_add_unless(atomic64_t *v, long long a, long long u)
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{
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unsigned low = (unsigned)u;
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unsigned high = (unsigned)(u >> 32);
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alternative_atomic64(add_unless,
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ASM_OUTPUT2("+A" (a), "+c" (v),
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"+S" (low), "+D" (high)),
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ASM_NO_INPUT_CLOBBER("memory"));
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return (int)a;
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}
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static inline int atomic64_inc_not_zero(atomic64_t *v)
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{
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int r;
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alternative_atomic64(inc_not_zero, "=&a" (r),
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"S" (v) : "ecx", "edx", "memory");
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return r;
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}
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static inline long long atomic64_dec_if_positive(atomic64_t *v)
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{
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long long r;
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alternative_atomic64(dec_if_positive, "=&A" (r),
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"S" (v) : "ecx", "memory");
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return r;
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}
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#undef alternative_atomic64
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#undef __alternative_atomic64
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#endif /* _ASM_X86_ATOMIC64_32_H */
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