Re: [Xen-devel] do_domctl and EAGAIN

To:	Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject:	Re: [Xen-devel] do_domctl and EAGAIN
From:	Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>
Date:	Tue, 07 Apr 2009 10:19:20 +0200
Cc:	"xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Keir Fraser wrote:
> On 07/04/2009 08:41, "Juergen Gross" <juergen.gross@xxxxxxxxxxxxxx> wrote:
> 
>> Keir Fraser wrote:
>>> Only DOMCTL_destroydomain returns EAGAIN. No domctl returns EINTR.
>> do_domctl uses ioctl.
>> ioctl can return EINTR if a signal is caught.
> 
> Our privcmd hypercall ioctl() is non-blocking and hence I don't think can
> return EINTR. In fact ioctl() is used in loads of places throughout our
> toolstack and in qemu, and I don't think EINTR is checked by any caller, nor
> is EINTR mentioned in the ioctl man page.

On my system the ioctl man page does mention it:

ERRORS
       Under the following general conditions, ioctl() shall fail if:

       EBADF  The fildes argument is not a valid open file descriptor.

       EINTR  A signal was caught during the ioctl() operation.


In the non-blocking case this might be irrelevant. Are you sure this is no
issue in any case?


Juergen

-- 
Juergen Gross                 Principal Developer Operating Systems
TSP ES&S SWE OS6                       Telephone: +49 (0) 89 636 47950
Fujitsu Technolgy Solutions               e-mail: juergen.gross@xxxxxxxxxxxxxx
Otto-Hahn-Ring 6                        Internet: ts.fujitsu.com
D-81739 Muenchen                 Company details: ts.fujitsu.com/imprint.html

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Re: [Xen-devel] do_domctl and EAGAIN