virtio: remove overzealous BUG_ON.

[linux-2.6-omap-h63xx.git] / include / linux / virtio.h

diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 260d1fcf29a4222c011ab39176b1e2e4d46a98a3..e7d10845b3c17be5c8bf26fa088a5c82c92e3af4 100644 (file)
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -41,13 +41,17 @@ struct virtqueue
  *     Returns NULL or the "data" token handed to add_buf.
  * @disable_cb: disable callbacks
  *     vq: the struct virtqueue we're talking about.
+ *     Note that this is not necessarily synchronous, hence unreliable and only
+ *     useful as an optimization.
  * @enable_cb: restart callbacks after disable_cb.
  *     vq: the struct virtqueue we're talking about.
- *     This returns "false" (and doesn't re-enable) if there are pending
- *     buffers in the queue, to avoid a race.
+ *     This re-enables callbacks; it returns "false" if there are pending
+ *     buffers in the queue, to detect a possible race between the driver
+ *     checking for more work, and enabling callbacks.
  *
  * Locking rules are straightforward: the driver is responsible for
- * locking.  No two operations may be invoked simultaneously.
+ * locking.  No two operations may be invoked simultaneously, with the exception
+ * of @disable_cb.
  *
  * All operations can be called in any context.
  */