diff options
| -rw-r--r-- | sys/src/cmd/cwfs/sub.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/sys/src/cmd/cwfs/sub.c b/sys/src/cmd/cwfs/sub.c index 656ad19b9..3f33310fa 100644 --- a/sys/src/cmd/cwfs/sub.c +++ b/sys/src/cmd/cwfs/sub.c @@ -917,12 +917,17 @@ hexdump(void *a, int n) fprint(2, "%s\n", s1); } +extern int cas(long *p, long ov, long nv); + void* fs_recv(Queue *q, int) { void *a; + long v; - semacquire(&q->count, 1); + v = q->count; + if(v == 0 || cas(&q->count, v, v-1) == 0) + semacquire(&q->count, 1); lock(&q->rl); a = *q->rp; if(++q->rp >= &q->args[q->size]) @@ -935,7 +940,11 @@ fs_recv(Queue *q, int) void fs_send(Queue *q, void *a) { - semacquire(&q->avail, 1); + long v; + + v = q->avail; + if(v == 0 || cas(&q->avail, v, v-1) == 0) + semacquire(&q->avail, 1); lock(&q->wl); *q->wp = a; if(++q->wp >= &q->args[q->size]) |