1991/1002/port/qlock.c (diff list | history)

port/qlock.c on 1991/0428
1991/0428		#include "u.h" #include "lib.h" #include "mem.h" #include "dat.h" #include "fns.h" void qlock(QLock *q) {
1991/1002		Proc *p, *mp;
1991/0428
1991/1002		lock(&q->use); if(!q->locked) { q->locked = 1; unlock(&q->use);
1991/0428		return; } p = q->tail;
1991/1002		mp = u->p;
1991/0428		if(p == 0)
1991/1002		q->head = mp;
1991/0428		else
1991/1002		p->qnext = mp; q->tail = mp; mp->qnext = 0; mp->state = Queueing; unlock(&q->use);
1991/0428		sched(); } int canqlock(QLock *q) {
1991/1002		lock(&q->use); if(q->locked) { unlock(&q->use); return 0; } q->locked = 1; unlock(&q->use); return 1;
1991/0428		} void qunlock(QLock *q) { Proc *p;
1991/1002		lock(&q->use); p = q->head; if(p) {
1991/0428		q->head = p->qnext; if(q->head == 0) q->tail = 0; unlock(&q->use);
1991/1002		ready(p); return;
1991/0428		}
1991/1002		q->locked = 0; unlock(&q->use);
1991/0428		}