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authorRusty Russell <rusty@rustcorp.com.au>2008-02-04 23:50:03 -0500
committerRusty Russell <rusty@rustcorp.com.au>2008-02-04 07:50:03 -0500
commit6e5aa7efb27aec7e55b6463fa2c8db594c4226fa (patch)
tree060a955e711ac224136157a5410e88dcdab965af /drivers/virtio/virtio.c
parentb3369c1fb410fddeb38a404316c861395f6d6ae8 (diff)
virtio: reset function
A reset function solves three problems: 1) It allows us to renegotiate features, eg. if we want to upgrade a guest driver without rebooting the guest. 2) It gives us a clean way of shutting down virtqueues: after a reset, we know that the buffers won't be used by the host, and 3) It helps the guest recover from messed-up drivers. So we remove the ->shutdown hook, and the only way we now remove feature bits is via reset. We leave it to the driver to do the reset before it deletes queues: the balloon driver, for example, needs to chat to the host in its remove function. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/virtio/virtio.c')
-rw-r--r--drivers/virtio/virtio.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 303cb6f90108..7dddb1860936 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -102,9 +102,13 @@ static int virtio_dev_remove(struct device *_d)
102 struct virtio_driver *drv = container_of(dev->dev.driver, 102 struct virtio_driver *drv = container_of(dev->dev.driver,
103 struct virtio_driver, driver); 103 struct virtio_driver, driver);
104 104
105 dev->config->set_status(dev, dev->config->get_status(dev)
106 & ~VIRTIO_CONFIG_S_DRIVER);
107 drv->remove(dev); 105 drv->remove(dev);
106
107 /* Driver should have reset device. */
108 BUG_ON(dev->config->get_status(dev));
109
110 /* Acknowledge the device's existence again. */
111 add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
108 return 0; 112 return 0;
109} 113}
110 114
@@ -130,6 +134,10 @@ int register_virtio_device(struct virtio_device *dev)
130 dev->dev.bus = &virtio_bus; 134 dev->dev.bus = &virtio_bus;
131 sprintf(dev->dev.bus_id, "%u", dev->index); 135 sprintf(dev->dev.bus_id, "%u", dev->index);
132 136
137 /* We always start by resetting the device, in case a previous
138 * driver messed it up. This also tests that code path a little. */
139 dev->config->reset(dev);
140
133 /* Acknowledge that we've seen the device. */ 141 /* Acknowledge that we've seen the device. */
134 add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); 142 add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
135 143