Re: [PATCH] video: hyperv: hyperv_fb: refresh the VM screen by force on VM panic

Greg KH
2014-06-26T03:36:27Z

On Tue, Jun 24, 2014 at 09:44:14PM +0000, Dexuan Cui wrote:
> >On Tue, Jun 24, 2014 at 08:29:17AM +0800, Dexuan Cui wrote:
> >> Currently the VSC has no chance to notify the VSP of the dirty rectangle on VM
> >> panic because the notification work is done in a workqueue, and in panic() the
> >> kernel typically ends up in an infinite loop, and a typical kernel config has
> >> CONFIG_PREEMPT_VOLUNTARY=y and CONFIG_PREEMPT is not set, so a context switch
> >> can't happen in panic() and the workqueue won't have a chance to run. As a
> >> result, the VM Connection window can't refresh until it's closed and we
> >> re-connect to the VM.
> >>
> >> We can register a handler on panic_notifier_list: the handler can notify
> >> the VSC and switch the framebuffer driver to a "synchronous mode", meaning
> >> the VSC flushes any future framebuffer change to the VSP immediately.
> >>
> >> MS-TFS: 157532
>
> > What is this line for?
>
> Hi Greg,
> This line is for our internal bug repository.
> We have an automated system to correlate bugs with fixes so that our test
> team knows when a bug fix has been accepted upstream and they need to
> write a new test case for it.
>
> The MS-TFS line has appeared in the commit description for a while if you
> search for it in 'git log' of linux-next.
>
> Please let us know if you have further comments.

Please don't add marker lines like this that provide no relevancy to
anyone else. I don't allow gerrit ids for the same reason. If you want
to refer to a public bug tracker, that's great, otherwise, don't
include it.

greg k-h