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/*
* Optimised mutex implementation of include/asm-generic/mutex-dec.h algorithm
*/
#ifndef _ASM_POWERPC_MUTEX_H
#define _ASM_POWERPC_MUTEX_H
static inline int __mutex_cmpxchg_lock(atomic_t *v, int old, int new)
{
int t;
__asm__ __volatile__ (
"1: lwarx %0,0,%1 # mutex trylock\n\
cmpw 0,%0,%2\n\
bne- 2f\n"
PPC405_ERR77(0,%1)
" stwcx. %3,0,%1\n\
bne- 1b"
PPC_ACQUIRE_BARRIER
"\n\
2:"
: "=&r" (t)
: "r" (&v->counter), "r" (old), "r" (new)
: "cc", "memory");
return t;
}
static inline int __mutex_dec_return_lock(atomic_t *v)
{
int t;
__asm__ __volatile__(
"1: lwarx %0,0,%1 # mutex lock\n\
addic %0,%0,-1\n"
PPC405_ERR77(0,%1)
" stwcx. %0,0,%1\n\
bne- 1b"
PPC_ACQUIRE_BARRIER
: "=&r" (t)
: "r" (&v->counter)
: "cc", "memory");
return t;
}
static inline int __mutex_inc_return_unlock(atomic_t *v)
{
int t;
__asm__ __volatile__(
PPC_RELEASE_BARRIER
"1: lwarx %0,0,%1 # mutex unlock\n\
addic %0,%0,1\n"
PPC405_ERR77(0,%1)
" stwcx. %0,0,%1 \n\
bne- 1b"
: "=&r" (t)
: "r" (&v->counter)
: "cc", "memory");
return t;
}
/**
* __mutex_fastpath_lock - try to take the lock by moving the count
* from 1 to a 0 value
* @count: pointer of type atomic_t
* @fail_fn: function to call if the original value was not 1
*
* Change the count from 1 to a value lower than 1, and call <fail_fn> if
* it wasn't 1 originally. This function MUST leave the value lower than
* 1 even when the "1" assertion wasn't true.
*/
static inline void
__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
{
if (unlikely(__mutex_dec_return_lock(count) < 0))
fail_fn(count);
}
/**
* __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(__mutex_dec_return_lock(count) < 0))
return -1;
return 0;
}
/**
* __mutex_fastpath_unlock - try to promote the count 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 count 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.
*/
static inline void
__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
{
if (unlikely(__mutex_inc_return_unlock(count) <= 0))
fail_fn(count);
}
#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 0, and return 1 (success), or if the count
* was not 1, then return 0 (failure).
*/
static inline int
__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
{
if (likely(atomic_read(count) == 1 && __mutex_cmpxchg_lock(count, 1, 0) == 1))
return 1;
return 0;
}
#endif
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