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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;
void
getcallerpcs(void *v, uint pcs[])
{
uint *ebp = (uint*)v - 2;
int i;
for(i = 0; i < 10 && ebp && ebp != (uint*)0xffffffff; ebp = (uint*)*ebp, i++){
pcs[i] = *(ebp + 1);
}
for( ; i < 10; i++)
pcs[i] = 0;
}
void
acquire(struct spinlock * lock)
{
if(holding(lock))
panic("acquire");
if(cpus[cpu()].nlock++ == 0)
cli();
while(cmpxchg(0, 1, &lock->locked) == 1)
;
cpuid(0, 0, 0, 0, 0); // memory barrier
getcallerpcs(&lock, lock->pcs);
lock->cpu = cpu() + 10;
cpus[cpu()].lastacquire = lock;
}
void
release(struct spinlock * lock)
{
if(!holding(lock))
panic("release");
cpus[cpu()].lastrelease = lock;
lock->pcs[0] = 0;
lock->cpu = 0xffffffff;
cpuid(0, 0, 0, 0, 0); // memory barrier
lock->locked = 0;
if(--cpus[cpu()].nlock == 0)
sti();
}
int
holding(struct spinlock *lock)
{
return lock->locked && lock->cpu == cpu() + 10;
}
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