summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorMichael S. Tsirkin <mst@redhat.com>2015-03-12 01:23:41 (GMT)
committerRusty Russell <rusty@rustcorp.com.au>2015-03-13 05:25:41 (GMT)
commit8051a2a518fcf3827a143470083ad6008697ff17 (patch)
treeb4175841d94bc9b3aef2e92a46e708e9856eea0e
parent3d2a3774c1b046f548ebea0391a602fd5685a307 (diff)
downloadlinux-8051a2a518fcf3827a143470083ad6008697ff17.tar.xz
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>
-rw-r--r--net/9p/trans_virtio.c24
1 files changed, 20 insertions, 4 deletions
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index d8e376a..36a1a73 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -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);