Re: [Xen-devel] [PATCH] xen-netfront: Fix hang on device removal

From: Simon Gaiser
Date: Thu Apr 19 2018 - 14:10:42 EST


Jason Andryuk:
> 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")

I think this should go into stable since AFAIK the hanging network
device can only be fixed by rebooting the guest. AFAICS this affects all
4.* branches since 5b5971df3bc2 got backported to them.

Upstream commit c2d2e6738a209f0f9dffa2dc8e7292fc45360d61.

Simon

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