xv6/spinlock.c

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#include "types.h"
#include "defs.h"
#include "x86.h"
#include "mmu.h"
#include "param.h"
#include "proc.h"
#include "spinlock.h"
// Can't call cprintf from inside these routines,
// because cprintf uses them itself.
#define cprintf dont_use_cprintf
extern int use_console_lock;
int
getcallerpc(void *v)
{
return ((int*)v)[-1];
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}
void
acquire1(struct spinlock * lock, struct proc *cp)
{
if(cpus[cpu()].nlock++ == 0)
cli();
while(cmpxchg(0, 1, &lock->locked) == 1)
;
cpuid(0, 0, 0, 0, 0); // memory barrier
lock->locker_pc = getcallerpc(&lock);
}
void
release1(struct spinlock * lock, struct proc *cp)
{
cpuid(0, 0, 0, 0, 0); // memory barrier
lock->locked = 0;
if(--cpus[cpu()].nlock == 0)
sti();
}
void
acquire(struct spinlock *lock)
{
acquire1(lock, curproc[cpu()]);
}
void
release(struct spinlock *lock)
{
release1(lock, curproc[cpu()]);
}