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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: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Michael S. Tsirkin 2015-03-12 11:53:41 +10:30 committed by Rusty Russell
parent 3d2a3774c1
commit 8051a2a518
1 changed files with 20 additions and 4 deletions
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24
net/9p/trans_virtio.c
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@ -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);