From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jan Beulich" <JBeulich@suse.com>
Subject: Re: [PATCH] switch hypercall restart indication from
 -EAGAIN to -ERESTART
Date: Thu, 15 May 2014 12:56:15 +0100
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To: Tim Deegan <tim@xen.org>
Cc: Kevin Tian <kevin.tian@intel.com>, Keir Fraser <keir@xen.org>, Jun Nakajima <jun.nakajima@intel.com>, Ian Jackson <Ian.Jackson@eu.citrix.com>, Eddie Dong <eddie.dong@intel.com>, Ian Campbell <Ian.Campbell@eu.citrix.com>, Stefano Stabellini <stefano.stabellini@citrix.com>, suravee.suthikulpanit@amd.com, xen-devel <xen-devel@lists.xenproject.org>, Aravind Gopalakrishnan <aravind.gopalakrishnan@amd.com>, Boris Ostrovsky <boris.ostrovsky@oracle.com>
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>>> On 15.05.14 at 13:24, <tim@xen.org> 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.

> 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.

Jan