Re: [Xen-devel] [PATCH-for-4.13 v5] Rationalize max_grant_frames and max_maptrack_frames handling

From: Anthony PERARD <anthony.perard@citrix.com>
To: "Durrant, Paul" <pdurrant@amazon.com>
Cc: "Stefano Stabellini" <sstabellini@kernel.org>,
	"Julien Grall" <julien@xen.org>, "Wei Liu" <wl@xen.org>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"George Dunlap" <George.Dunlap@eu.citrix.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Ian Jackson" <ian.jackson@eu.citrix.com>,
	"George Dunlap" <george.dunlap@citrix.com>,
	"Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>,
	"Jan Beulich" <jbeulich@suse.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	"Volodymyr Babchuk" <Volodymyr_Babchuk@epam.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH-for-4.13 v5] Rationalize max_grant_frames and max_maptrack_frames handling
Date: Fri, 29 Nov 2019 13:52:04 +0000	[thread overview]
Message-ID: <20191129135204.GE1155@perard.uk.xensource.com> (raw)
In-Reply-To: <b6aa51e207aa44eca1acb027e5765d24@EX13D32EUC003.ant.amazon.com>

On Fri, Nov 29, 2019 at 12:51:47PM +0000, Durrant, Paul wrote:
> > -----Original Message-----
> > From: Anthony PERARD <anthony.perard@citrix.com>
> > Sent: 29 November 2019 12:46
> > I'm not sure what was the intention with the new function
> > xlu_cfg_get_bounded_long(), but I don't think libxlu is the right place
> > for it. That function is only going to make it harder for users to find
> > mistakes in the config file. If `n' value is out of bound, it will only
> > get ignored, and xl will keep going. I think xlu_cfg should only be a
> > parser (and can check for syntax error).
> > 
> > Can you move that function to xl?
> > 
> 
> I can, but why is this not considered useful in libxl? The call returns failure for an out-of-bounds check.

Sorry that the repo layout is confusing, but libxl != libxlu. libxl
doesn't even use libxlu!

> If xl currently chooses to treat EINVAL as ENOENT then that's xl's bug to deal with.

The general use of xlu_cfg_get_*() that treats all errors as ENOENT in
xl is an issue, I think, but this patch does the same thing and treat
EINVAL as ENOENT when using the newly introduced
xlu_cfg_get_bounded_long() function. I don't think that an xl bug to
deal with, but an issue with the patch.

Cheers,

-- 
Anthony PERARD

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