Release 4.8 arch/x86/include/asm/mutex_32.h
/*
* Assembly implementation of the mutex fastpath, based on atomic
* decrement/increment.
*
* started by Ingo Molnar:
*
* Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
*/
#ifndef _ASM_X86_MUTEX_32_H
#define _ASM_X86_MUTEX_32_H
#include <asm/alternative.h>
/**
* __mutex_fastpath_lock - try to take the lock by moving the count
* from 1 to a 0 value
* @count: pointer of type atomic_t
* @fn: function to call if the original value was not 1
*
* Change the count from 1 to a value lower than 1, and call <fn> if it
* wasn't 1 originally. This function MUST leave the value lower than 1
* even when the "1" assertion wasn't true.
*/
#define __mutex_fastpath_lock(count, fail_fn) \
do { \
unsigned int dummy; \
\
typecheck(atomic_t *, count); \
typecheck_fn(void (*)(atomic_t *), fail_fn); \
\
asm volatile(LOCK_PREFIX " decl (%%eax)\n" \
" jns 1f \n" \
" call " #fail_fn "\n" \
"1:\n" \
: "=a" (dummy) \
: "a" (count) \
: "memory", "ecx", "edx"); \
} while (0)
/**
* __mutex_fastpath_lock_retval - try to take the lock by moving the count
* from 1 to a 0 value
* @count: pointer of type atomic_t
*
* Change the count from 1 to a value lower than 1. This function returns 0
* if the fastpath succeeds, or -1 otherwise.
*/
static inline int __mutex_fastpath_lock_retval(atomic_t *count)
{
if (unlikely(atomic_dec_return(count) < 0))
return -1;
else
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| arjan van de ven | arjan van de ven | 26 | 83.87% | 1 | 33.33% |
| harvey harrison | harvey harrison | 3 | 9.68% | 1 | 33.33% |
| maarten lankhorst | maarten lankhorst | 2 | 6.45% | 1 | 33.33% |
| Total | 31 | 100.00% | 3 | 100.00% |
/**
* __mutex_fastpath_unlock - try to promote the mutex from 0 to 1
* @count: pointer of type atomic_t
* @fail_fn: function to call if the original value was not 0
*
* try to promote the mutex from 0 to 1. if it wasn't 0, call <fail_fn>.
* In the failure case, this function is allowed to either set the value
* to 1, or to set it to a value lower than 1.
*
* If the implementation sets it to a value of lower than 1, the
* __mutex_slowpath_needs_to_unlock() macro needs to return 1, it needs
* to return 0 otherwise.
*/
#define __mutex_fastpath_unlock(count, fail_fn) \
do { \
unsigned int dummy; \
\
typecheck(atomic_t *, count); \
typecheck_fn(void (*)(atomic_t *), fail_fn); \
\
asm volatile(LOCK_PREFIX " incl (%%eax)\n" \
" jg 1f\n" \
" call " #fail_fn "\n" \
"1:\n" \
: "=a" (dummy) \
: "a" (count) \
: "memory", "ecx", "edx"); \
} while (0)
#define __mutex_slowpath_needs_to_unlock() 1
/**
* __mutex_fastpath_trylock - try to acquire the mutex, without waiting
*
* @count: pointer of type atomic_t
* @fail_fn: fallback function
*
* Change the count from 1 to a value lower than 1, and return 0 (failure)
* if it wasn't 1 originally, or return 1 (success) otherwise. This function
* MUST leave the value lower than 1 even when the "1" assertion wasn't true.
* Additionally, if the value was < 0 originally, this function must not leave
* it to 0 on failure.
*/
static inline int __mutex_fastpath_trylock(atomic_t *count,
int (*fail_fn)(atomic_t *))
{
/* cmpxchg because it never induces a false contention state. */
if (likely(atomic_read(count) == 1 && atomic_cmpxchg(count, 1, 0) == 1))
return 1;
return 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| arjan van de ven | arjan van de ven | 42 | 82.35% | 1 | 25.00% |
| peter zijlstra | peter zijlstra | 7 | 13.73% | 1 | 25.00% |
| borislav petkov | borislav petkov | 1 | 1.96% | 1 | 25.00% |
| linus torvalds | linus torvalds | 1 | 1.96% | 1 | 25.00% |
| Total | 51 | 100.00% | 4 | 100.00% |
#endif /* _ASM_X86_MUTEX_32_H */
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| arjan van de ven | arjan van de ven | 101 | 81.45% | 1 | 10.00% |
| peter zijlstra | peter zijlstra | 7 | 5.65% | 1 | 10.00% |
| joe perches | joe perches | 3 | 2.42% | 2 | 20.00% |
| h. peter anvin | h. peter anvin | 3 | 2.42% | 1 | 10.00% |
| maarten lankhorst | maarten lankhorst | 3 | 2.42% | 1 | 10.00% |
| harvey harrison | harvey harrison | 3 | 2.42% | 1 | 10.00% |
| gerd hoffmann | gerd hoffmann | 2 | 1.61% | 1 | 10.00% |
| borislav petkov | borislav petkov | 1 | 0.81% | 1 | 10.00% |
| linus torvalds | linus torvalds | 1 | 0.81% | 1 | 10.00% |
| Total | 124 | 100.00% | 10 | 100.00% |
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