+
+ /*
+ * 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;
+ }
+