use test-and-set for spin lock

diff --git a/kthread.c b/kthread.c
index d927ced5b718bc7f54f892c818f6ca5979486448..981215f41c4bc2d8918e2dd98054fa3968e5ba68 100644 (file)
--- a/kthread.c
+++ b/kthread.c
@@ -38,26 +38,26 @@ void dq_destroy(deque_t *d)
 int dq_enq(deque_t *q, int is_back, const dqval_t *v)
 {
        int ret = 0;
-       while (!__sync_bool_compare_and_swap(&q->lock, 0, 1));
+       while (__sync_lock_test_and_set(&q->lock, 1));
        if (!dq_is_full(q)) {
                q->a[(is_back? q->first + q->count : q->first + q->mask) & q->mask] = *v;
                q->first = is_back? q->first : q->first? q->first - 1 : q->mask;
                ++q->count;
        } else ret = -1;
-       while (!__sync_bool_compare_and_swap(&q->lock, 1, 0));
+       __sync_lock_release(&q->lock);
        return ret;
 }
 
 int dq_deq(deque_t *q, int is_back, dqval_t *v)
 {
        int ret = 0;
-       while (!__sync_bool_compare_and_swap(&q->lock, 0, 1));
+       while (__sync_lock_test_and_set(&q->lock, 1));
        if (dq_size(q)) {
                *v = q->a[is_back? (q->first + q->count + q->mask) & q->mask : q->first];
                q->first = is_back? q->first : q->first == q->mask? 0 : q->first + 1;
                --q->count;
        } else ret = -1;
-       while (!__sync_bool_compare_and_swap(&q->lock, 1, 0));
+       __sync_lock_release(&q->lock);
        return 0;
 }