void
lock(struct lock *l)
{
struct proc *p;
if (up == nil) {
return;
}
retry:
if (!cas(&l->holder, nil, up)) {
p = l->wlist;
while (p != nil && p->next != nil)
p = p->next;
up->next = nil;
if (p == nil) {
if (!cas(&l->wlist, nil, up)) {
goto retry;
}
} else if (!cas(&p->next, nil, up)) {
goto retry;
}
procwait();
}
}
Waitmsg*
runprocfd(char *file, char **v, int fd[3])
{
int pid, i;
threadwaitchan();
pid = threadspawn(fd, file, v);
for(i=0; i<3; i++)
close(fd[i]);
if(pid < 0)
return nil;
return procwait(pid);
}
bool
procwaitintr(int irqn)
{
intrstate_t t;
if (irqn < 0 || irqn > nirq) {
return false;
} else if (handlers[irqn] != nil) {
return false;
}
if (!cas(&waiting[irqn], nil, up)) {
return false;
}
t = setintr(INTR_off);
unmaskintr(irqn);
procwait();
setintr(t);
return true;
}
