ACK: [SRU][B/aws, F/aws, G/aws][PATCH 0/1] xen-netfront: prevent potential error on hibernate

[William Breathitt Gray]

On Fri, Dec 04, 2020 at 05:12:17PM +0100, Andrea Righi wrote:
> BugLink: https://bugs.launchpad.net/bugs/1906850
> 
> [Impact]
> 
> On hibernation xen-netfront is setting the device state on the xenbus to
> "Closing" and then it's waiting for the backend state to acknowledge
> that state (with a timeout). However, if the device is already in the
> state "Closed" this opteration will always hit the timeout, preventing
> the system to hibernate correctly.
> 
> [Test case]
> 
> It is a quite rare condition that can be reproduced hibernating/resuming
> a Xen instance multiple times. When the problem happens we should see in
> the log a Xen error message like the following:
> 
>   Freezing timed out; the device may become inconsistent state
> 
> [Fix]
> 
> If the device is already in the state "Closed", simply tear it down
> without notifying the Xen backend.
> 
> [Regression potential]
> 
> The fix would just prevent aborting hibernation if the netfront device
> is already in a "Closed" state. The resume callback is forcing the
> device into the "Initializing" state anyway, basically forcing a reset
> of the device, so nothing else in the state machine can be potentially
> broken.

Trivial fix and makes sense.

Acked-by: William Breathitt Gray <william.gray at canonical.com>
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