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/*
* smpprim.h: SMP locking primitives on the Sparc
*
* God knows we won't be actually using this code for some time
* but I thought I'd write it since I knew how.
*
* Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
*/
#ifndef __SPARC_SMPPRIM_H
#define __SPARC_SMPPRIM_H
/* Test and set the unsigned byte at ADDR to 1. Returns the previous
* value. On the Sparc we use the ldstub instruction since it is
* atomic.
*/
static inline __volatile__ char test_and_set(void *addr)
{
char state = 0;
__asm__ __volatile__("ldstub [%0], %1 ! test_and_set\n\t"
"=r" (addr), "=r" (state) :
"0" (addr), "1" (state) : "memory");
return state;
}
/* Initialize a spin-lock. */
static inline __volatile__ smp_initlock(void *spinlock)
{
/* Unset the lock. */
*((unsigned char *) spinlock) = 0;
return;
}
/* This routine spins until it acquires the lock at ADDR. */
static inline __volatile__ smp_lock(void *addr)
{
while(test_and_set(addr) == 0xff)
;
/* We now have the lock */
return;
}
/* This routine releases the lock at ADDR. */
static inline __volatile__ smp_unlock(void *addr)
{
*((unsigned char *) addr) = 0;
}
#endif /* !(__SPARC_SMPPRIM_H) */
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