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 14e1379876d334f9bb99d04d43750c571c967528..e7d10845b3c17be5c8bf26fa088a5c82c92e3af4 100644 (file)
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -11,15 +11,13 @@
 /**
  * virtqueue - a queue to register buffers for sending or receiving.
  * @callback: the function to call when buffers are consumed (can be NULL).
- *    If this returns false, callbacks are suppressed until vq_ops->restart
- *    is called.
  * @vdev: the virtio device this queue was created for.
  * @vq_ops: the operations for this virtqueue (see below).
  * @priv: a pointer for the virtqueue implementation to use.
  */
 struct virtqueue
 {
-       bool (*callback)(struct virtqueue *vq);
+       void (*callback)(struct virtqueue *vq);
        struct virtio_device *vdev;
        struct virtqueue_ops *vq_ops;
        void *priv;
@@ -41,16 +39,19 @@ struct virtqueue
  *     vq: the struct virtqueue we're talking about.
  *     len: the length written into the buffer
  *     Returns NULL or the "data" token handed to add_buf.
- * @restart: restart callbacks after callback returned false.
+ * @disable_cb: disable callbacks
  *     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.
- * @shutdown: "unadd" all buffers.
+ *     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.
- *     Remove everything from the queue.
+ *     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.
  */
@@ -65,9 +66,8 @@ struct virtqueue_ops {
 
        void *(*get_buf)(struct virtqueue *vq, unsigned int *len);
 
-       bool (*restart)(struct virtqueue *vq);
-
-       void (*shutdown)(struct virtqueue *vq);
+       void (*disable_cb)(struct virtqueue *vq);
+       bool (*enable_cb)(struct virtqueue *vq);
 };
 
 /**
@@ -97,12 +97,15 @@ void unregister_virtio_device(struct virtio_device *dev);
  * @probe: the function to call when a device is found.  Returns a token for
  *    remove, or PTR_ERR().
  * @remove: the function when a device is removed.
+ * @config_changed: optional function to call when the device configuration
+ *    changes; may be called in interrupt context.
  */
 struct virtio_driver {
        struct device_driver driver;
        const struct virtio_device_id *id_table;
        int (*probe)(struct virtio_device *dev);
        void (*remove)(struct virtio_device *dev);
+       void (*config_changed)(struct virtio_device *dev);
 };
 
 int register_virtio_driver(struct virtio_driver *drv);