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SubjectRE: [PATCH] PCI: hv: Do not wait forever on a device that has disappeared
Date
> From: Andy Shevchenko <andy.shevchenko@gmail.com>
> Sent: Tuesday, May 29, 2018 14:21
> On Thu, May 24, 2018 at 12:12 AM, Dexuan Cui <decui@microsoft.com>
> wrote:
> >
> > Before the guest finishes the device initialization, the device can be
> > removed anytime by the host, and after that the host won't respond to
> > the guest's request, so the guest should be prepared to handle this
> > case.
>
> > + while (true) {
> > + if (hdev->channel->rescind) {
> > + dev_warn_once(&hdev->device, "The device is
> gone.\n");
> > + return -ENODEV;
> > + }
> > +
> > + if (wait_for_completion_timeout(comp, HZ / 10))
> > + break;
> > + }
>
> Infinite loops are usually a red flags.
>
> What's wrong with simple:
>
> do {
> ...
> } while (wait_...(...) == 0);
>
> ?
Thanks for the suggestion, Andy!
The coding style you suggested looks better to me. :-)

> > + if (!ret)
> > + ret = wait_for_response(hdev, &comp);
>
> Better to use well established patterns, i.e.
>
> if (ret)
> return ret;
Agreed.

>
> > + if (!ret)
> > + ret = wait_for_response(hdev,
> &comp_pkt.host_event);
>
> Here it looks okay on the first glance, but better to think about it
> again and refactor.

> With Best Regards,
> Andy Shevchenko

I'll try to send out a patch to improve the coding style, after I address
Michael Kelley's concern of a race.

Thanks,
-- Dexuan
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