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[Xen-devel] Re: [PATCH] libxl: initialize domid to 0 in libxl__create_st

To: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
Subject: [Xen-devel] Re: [PATCH] libxl: initialize domid to 0 in libxl__create_stubdom
From: Wei Liu <liuw@xxxxxxxxx>
Date: Thu, 09 Jun 2011 16:31:27 +0800
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Stefano Stabellini <Stefano.Stabellini@xxxxxxxxxxxxx>
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On Thu, 2011-06-09 at 08:55 +0100, Ian Campbell wrote:
> On Thu, 2011-06-09 at 06:03 +0100, Wei Liu wrote:
> > The uninitialized domid may cause libxl__domain_make to fail.
> > 
> > In libxl__domain_make:
> > assert(!libxl_domid_valid_guest(*domid)).
> > 
> > Signed-off-by: Wei Liu <liuw@xxxxxxxxx>
> That check seems pretty odd to me at first but the commit message of
> 22842:ccfa0527893e does a good job of explaining why so: 
> Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> although it's not clear why libxl__domain_make doesn't just set an
> invalid value as it's first act and save the callers the effort, the net
> result would still be the correct semantics for libxl_domid_valid_guest
> when the function exits.

I think the commit message of 22842:ccfa0527893e says pretty clear that
it is caller's responsibility to initialize domid to a invalid value.

However, libxl__make_domain sets domid=-1 a few lines after the check.
This confuses me.

> Ian.

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