Message ID | ffa564996c79c0c69d908aadfcc97bc4af6ab816.1526499838.git.joseph.salisbury@canonical.com |
---|---|
State | New |
Headers | show |
Series | [SRU,Bionic,1/1] xen-netfront: Fix hang on device removal | expand |
On 18/05/18 15:59, Joseph Salisbury wrote: > From: Jason Andryuk <jandryuk@gmail.com> > > BugLink: http://bugs.launchpad.net/bugs/1771620 > > 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> > (cherry picked from commit c2d2e6738a209f0f9dffa2dc8e7292fc45360d61) > Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com> > --- > drivers/net/xen-netfront.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > index 9bd7dde..5a37ee2 100644 > --- a/drivers/net/xen-netfront.c > +++ b/drivers/net/xen-netfront.c > @@ -2007,7 +2007,10 @@ static void netback_changed(struct xenbus_device *dev, > case XenbusStateInitialised: > case XenbusStateReconfiguring: > case XenbusStateReconfigured: > + break; > + > case XenbusStateUnknown: > + wake_up_all(&module_unload_q); > break; > > case XenbusStateInitWait: > @@ -2138,7 +2141,9 @@ static int xennet_remove(struct xenbus_device *dev) > 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, > Clean upstream cherry pick that fixes the issue, positive test results, and limited to specific arch so limited regression potential. Acked-by: Colin Ian King <colin.king@canonical.com>
On 05/18/18 16:59, Joseph Salisbury wrote: > From: Jason Andryuk <jandryuk@gmail.com> > > BugLink: http://bugs.launchpad.net/bugs/1771620 > > 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> > (cherry picked from commit c2d2e6738a209f0f9dffa2dc8e7292fc45360d61) > Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com> > --- > drivers/net/xen-netfront.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c > index 9bd7dde..5a37ee2 100644 > --- a/drivers/net/xen-netfront.c > +++ b/drivers/net/xen-netfront.c > @@ -2007,7 +2007,10 @@ static void netback_changed(struct xenbus_device *dev, > case XenbusStateInitialised: > case XenbusStateReconfiguring: > case XenbusStateReconfigured: > + break; > + > case XenbusStateUnknown: > + wake_up_all(&module_unload_q); > break; > > case XenbusStateInitWait: > @@ -2138,7 +2141,9 @@ static int xennet_remove(struct xenbus_device *dev) > 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, > Clean cherry-pick, limited scope and tested by the reporter. Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Applied to bionic master-next. -Stefan
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 9bd7dde..5a37ee2 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -2007,7 +2007,10 @@ static void netback_changed(struct xenbus_device *dev, case XenbusStateInitialised: case XenbusStateReconfiguring: case XenbusStateReconfigured: + break; + case XenbusStateUnknown: + wake_up_all(&module_unload_q); break; case XenbusStateInitWait: @@ -2138,7 +2141,9 @@ static int xennet_remove(struct xenbus_device *dev) 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,