void
ilock(Lock *l)
{
Proc *up = externup();
Mpl pl;
uintptr_t pc;
uint64_t t0;
pc = getcallerpc();
lockstats.locks++;
pl = splhi();
if(TAS(&l->key) != 0){
cycles(&t0);
lockstats.glare++;
/*
* Cannot also check l->pc, l->m, or l->isilock here
* because they might just not be set yet, or
* (for pc and m) the lock might have just been unlocked.
*/
for(;;){
lockstats.inglare++;
splx(pl);
while(l->key)
;
pl = splhi();
if(TAS(&l->key) == 0){
if(l != &waitstatslk)
addwaitstat(pc, t0, WSlock);
goto acquire;
}
}
}
acquire:
machp()->ilockdepth++;
if(up)
up->lastilock = l;
l->pl = pl;
l->_pc = pc;
l->p = up;
l->isilock = 1;
l->m = machp();
if(LOCKCYCLES)
cycles(&l->lockcycles);
}
int
lock(Lock *l)
{
Proc *up = externup();
int i;
uintptr_t pc;
uint64_t t0;
pc = getcallerpc();
lockstats.locks++;
if(up)
ainc(&up->nlocks); /* prevent being scheded */
if(TAS(&l->key) == 0){
if(up)
up->lastlock = l;
l->_pc = pc;
l->p = up;
l->isilock = 0;
if(LOCKCYCLES)
cycles(&l->lockcycles);
return 0;
}
if(up)
adec(&up->nlocks);
cycles(&t0);
lockstats.glare++;
for(;;){
lockstats.inglare++;
i = 0;
while(l->key){
if(sys->nmach < 2 && up && up->edf && (up->edf->flags & Admitted)){
/*
* Priority inversion, yield on a uniprocessor; on a
* multiprocessor, the other processor will unlock
*/
print("inversion %#p pc %#p proc %d held by pc %#p proc %d\n",
l, pc, up ? up->pid : 0, l->_pc, l->p ? l->p->pid : 0);
up->edf->d = todget(nil); /* yield to process with lock */
}
if(i++ > 100000000){
i = 0;
lockloop(l, pc);
}
}
if(up)
ainc(&up->nlocks);
if(TAS(&l->key) == 0){
if(up)
up->lastlock = l;
l->_pc = pc;
l->p = up;
l->isilock = 0;
if(LOCKCYCLES)
cycles(&l->lockcycles);
if(l != &waitstatslk)
addwaitstat(pc, t0, WSlock);
return 1;
}
if(up)
adec(&up->nlocks);
}
}
static void
slockstat(uintptr_t pc, uint64_t w)
{
addwaitstat(pc, w, WSslock);
}