| From c2d2e6738a209f0f9dffa2dc8e7292fc45360d61 Mon Sep 17 00:00:00 2001 |
| From: Jason Andryuk <jandryuk@gmail.com> |
| Date: Wed, 28 Feb 2018 07:23:23 -0500 |
| Subject: xen-netfront: Fix hang on device removal |
| |
| From: Jason Andryuk <jandryuk@gmail.com> |
| |
| commit c2d2e6738a209f0f9dffa2dc8e7292fc45360d61 upstream. |
| |
| A toolstack may delete the vif frontend and backend xenstore entries |
| while xen-netfront is in the removal code path. In that case, the |
| checks for xenbus_read_driver_state would return XenbusStateUnknown, and |
| xennet_remove would hang indefinitely. This hang prevents system |
| shutdown. |
| |
| xennet_remove must be able to handle XenbusStateUnknown, and |
| netback_changed must also wake up the wake_queue for that state as well. |
| |
| Fixes: 5b5971df3bc2 ("xen-netfront: remove warning when unloading module") |
| |
| Signed-off-by: Jason Andryuk <jandryuk@gmail.com> |
| Cc: Eduardo Otubo <otubo@redhat.com> |
| Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> |
| Signed-off-by: Juergen Gross <jgross@suse.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/net/xen-netfront.c | 7 ++++++- |
| 1 file changed, 6 insertions(+), 1 deletion(-) |
| |
| --- a/drivers/net/xen-netfront.c |
| +++ b/drivers/net/xen-netfront.c |
| @@ -2067,7 +2067,10 @@ static void netback_changed(struct xenbu |
| case XenbusStateInitialised: |
| case XenbusStateReconfiguring: |
| case XenbusStateReconfigured: |
| + break; |
| + |
| case XenbusStateUnknown: |
| + wake_up_all(&module_unload_q); |
| break; |
| |
| case XenbusStateInitWait: |
| @@ -2314,7 +2317,9 @@ static int xennet_remove(struct xenbus_d |
| xenbus_switch_state(dev, XenbusStateClosing); |
| wait_event(module_unload_q, |
| xenbus_read_driver_state(dev->otherend) == |
| - XenbusStateClosing); |
| + XenbusStateClosing || |
| + xenbus_read_driver_state(dev->otherend) == |
| + XenbusStateUnknown); |
| |
| xenbus_switch_state(dev, XenbusStateClosed); |
| wait_event(module_unload_q, |