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Re: [Xen-devel] [PATCH] libxc: make unlock_page return error

To: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] libxc: make unlock_page return error
From: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Date: Thu, 19 Aug 2010 15:57:21 +0100
Cc: Christoph Egger <Christoph.Egger@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
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On Thu, 2010-08-19 at 15:46 +0100, Ian Jackson wrote:
> Christoph Egger writes ("[Xen-devel] [PATCH] libxc: make unlock_page return 
> error"):
> > As a result of debugging 'xend segfaults when starting',
> > the attached patch makes unlock_pages return an error.
> Having read this in more detail, it seems that you're making
> {lock,unlock}_pages return errno values on error.  That's fine but
> it's quite unusual in libxc; all libxc functions normally return -1 on
> error and set errno.
> So I think the unusual return value convention is worth a comment in
> xc_private.h.  Can you please resubmit with such a comment ?

I think it should just follow the normal libxc convention instead of
commenting on the use of an unusual return value convention.

I also think that such a patch must include (or be part of a series
which) updates the callers to actually do something with the new return
value, or else it is somewhat pointless.

Given that this patch was only for debugging purposes for an issue which
is now resolved is there any need?


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