Re: [Xen-devel] [PATCH] switch hypercall restart indication from -EAGAIN to -ERESTART

[Tim Deegan <tim@xxxxxxx>]

At 12:56 +0100 on 15 May (1400154975), Jan Beulich wrote:
> >>> On 15.05.14 at 13:24, <tim@xxxxxxx> wrote:
> > Some of the paths are a bit complex now, e.g. a preemption
> > point being reported as EINTR by __put_page_type(), translated to
> > ERESTART by relinquish_memory(), then to EAGAIN by domain_kill().
> 
> That second conversion I expect to go away anyway - we shouldn't
> really rely on the tools to do the hypercall re-invocations. I've got
> this as part of another domctl/XSA-77 follow-up patch already.

OK.

> > Are there cases where we want to return EINTR to the guest, or could
> > we maybe use it everywhere and drop ERESTART?
> 
> No, we need two distinct error codes on these paths. For now we
> never need to return -EINTR to the guest (and for now I also can't
> see when/why we would), but we'd have to convert these too
> should the need arise.

I didn't really understand that.  Do you mean that there's a reason to
have both EINTR and ERESTART even though we don't return EINTR to
guests, or that you want to keep them separate in case we ever do
want to return EINTR?

Tim.


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