Re: [Xen-devel] [PATCH] xen/pci: make bus notifier handler return sane values

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 17.08.11 at 17:31, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> On Wed, Aug 17, 2011 at 04:18:35PM +0100, Jan Beulich wrote:
>> >>> On 17.08.11 at 16:57, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> 
>> >>> wrote:
>> > On Wed, Aug 17, 2011 at 09:32:32AM +0100, Jan Beulich wrote:
>> >> Notifier functions are expected to return NOTIFY_* codes, not -E...
>> >> ones. In particular, since the respective hypercalls failing is not
>> >> fatal to the operation of the Dom0 kernel, it must be avoided to
>> > 
>> > So if we fail adding a PCI device, won't we be unable to actually
>> > setup its MSI?
>> 
>> Sure (and you also can't pass through such a device), but that's no
>> reason to fail the notification chain. For one, you don't know whether
>> the driver is actually going to use MSI. And even if you knew, it would
>> be bad behavior imo. Plus even if you want to fail the notifier chain,
>> just returning a -E... value here is wrong; notifier_from_errno() ought
>> to be used then.
> 
> Oh, I am not disputing that. I am just wondering whether we should add
> some extra printk's if we fail, and still reutrn either NOTIFY_OK
> oir NOTIFY_DONE.
> 
> That way at least in the field we will have a good inkling of what
> went wrong.

Ah - I just assumed this being silent is intentional, and didn't want to
override whoever decided so. We're in agreement then that this
could/should change.

Jan


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