From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Andryuk Subject: [PATCH] xen-netfront: Fix hang on device removal Date: Wed, 28 Feb 2018 07:23:23 -0500 Message-ID: <20180228122323.3914-1-jandryuk@gmail.com> Cc: Jason Andryuk , Eduardo Otubo , Boris Ostrovsky , Juergen Gross , linux-kernel@vger.kernel.org (open list) To: xen-devel@lists.xenproject.org, netdev@vger.kernel.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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 Cc: Eduardo Otubo --- 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 8328d395e332..3127bc8633ca 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -2005,7 +2005,10 @@ 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: @@ -2136,7 +2139,9 @@ 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, -- 2.14.3