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Commit 8051a2a5 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Rusty Russell
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9p/trans_virtio: fix hot-unplug 



On device hot-unplug, 9p/virtio currently will kfree channel while
it might still be in use.

Of course, it might stay used forever, so it's an extremely ugly hack,
but it seems better than use-after-free that we have now.

[ Unused variable removed, whitespace cleanup, msg single-lined --RR ]
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 3d2a3774

net/9p/trans_virtio.c

+20 −4
Original line number Diff line number Diff line
@@ -658,14 +658,30 @@ p9_virtio_create(struct p9_client *client, const char *devname, char *args) 
static void p9_virtio_remove(struct virtio_device *vdev)

{

	struct virtio_chan *chan = vdev->priv;



	if (chan->inuse)

		p9_virtio_close(chan->client);

	vdev->config->del_vqs(vdev);

	unsigned long warning_time;



	mutex_lock(&virtio_9p_lock);



	/* Remove self from list so we don't get new users. */

	list_del(&chan->chan_list);

	warning_time = jiffies;



	/* Wait for existing users to close. */

	while (chan->inuse) {

		mutex_unlock(&virtio_9p_lock);

		msleep(250);

		if (time_after(jiffies, warning_time + 10 * HZ)) {

			dev_emerg(&vdev->dev,

				  "p9_virtio_remove: waiting for device in use.\n");

			warning_time = jiffies;

		}

		mutex_lock(&virtio_9p_lock);

	}



	mutex_unlock(&virtio_9p_lock);



	vdev->config->del_vqs(vdev);



	sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);

	kobject_uevent(&(vdev->dev.kobj), KOBJ_CHANGE);

	kfree(chan->tag);