diff options
| -rw-r--r-- | sys/src/libc/9sys/qlock.c | 37 |
1 files changed, 22 insertions, 15 deletions
diff --git a/sys/src/libc/9sys/qlock.c b/sys/src/libc/9sys/qlock.c index 44cce8ab8..e968080be 100644 --- a/sys/src/libc/9sys/qlock.c +++ b/sys/src/libc/9sys/qlock.c @@ -175,8 +175,8 @@ runlock(RWLock *q) if(p->state != QueuingW) abort(); q->head = p->next; - if(q->head == 0) - q->tail = 0; + if(q->head == nil) + q->tail = nil; q->writer = 1; unlock(&q->lock); @@ -233,7 +233,7 @@ canwlock(RWLock *q) void wunlock(RWLock *q) { - QLp *p; + QLp *p, *x; lock(&q->lock); if(q->writer == 0) @@ -254,24 +254,31 @@ wunlock(RWLock *q) ; return; } - if(p->state != QueuingR) abort(); - q->writer = 0; - do { - /* wake waiting readers */ - q->head = p->next; - if(q->head == nil) - q->tail = nil; + /* collect waiting readers */ + q->readers = 1; + for(x = p->next; x != nil && x->state == QueuingR; x = x->next){ q->readers++; - unlock(&q->lock); + p = x; + } + p->next = nil; + p = q->head; + + /* queue remaining writers */ + q->head = x; + if(x == nil) + q->tail = nil; + q->writer = 0; + unlock(&q->lock); + + /* wakeup waiting readers */ + for(; p != nil; p = x){ + x = p->next; while((*_rendezvousp)(p, 0) == (void*)~0) ; - lock(&q->lock); - p = q->head; - } while(p != nil && p->state == QueuingR && q->writer == 0); - unlock(&q->lock); + } } void |