*/
return;
- if (unlikely(!__test_and_clear_bit(tag, bqt->tag_map))) {
- printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",
- __FUNCTION__, tag);
- return;
- }
-
list_del_init(&rq->queuelist);
rq->cmd_flags &= ~REQ_QUEUED;
rq->tag = -1;
__FUNCTION__, tag);
bqt->tag_index[tag] = NULL;
+
+ /*
+ * We use test_and_clear_bit's memory ordering properties here.
+ * The tag_map bit acts as a lock for tag_index[bit], so we need
+ * a barrer before clearing the bit (precisely: release semantics).
+ * Could use clear_bit_unlock when it is merged.
+ */
+ if (unlikely(!test_and_clear_bit(tag, bqt->tag_map))) {
+ printk(KERN_ERR "%s: attempt to clear non-busy tag (%d)\n",
+ __FUNCTION__, tag);
+ return;
+ }
+
bqt->busy--;
}
return 1;
} while (test_and_set_bit(tag, bqt->tag_map));
+ /*
+ * We rely on test_and_set_bit providing lock memory ordering semantics
+ * (could use test_and_set_bit_lock when it is merged).
+ */
rq->cmd_flags |= REQ_QUEUED;
rq->tag = tag;