From: David Vrabel <david.vrabel@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
xen-devel@lists.xensource.com,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Andres Lagar-Cavilla <andreslc@gridcentric.ca>,
kernel-janitors@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Dan Carpenter <dan.carpenter@oracle.com>
Subject: Re: [Xen-devel] [patch 3/3] xen/privcmd: remove const modifier from declaration
Date: Mon, 10 Sep 2012 10:43:19 +0000 [thread overview]
Message-ID: <504DC447.9010301@citrix.com> (raw)
In-Reply-To: <504DC8FE020000780009A190@nat28.tlf.novell.com>
On 10/09/12 10:03, Jan Beulich wrote:
>>>> On 08.09.12 at 11:58, Dan Carpenter <dan.carpenter@oracle.com> wrote:
>> When we use this pointer, we cast away the const modifier and modify the
>> data. I think it was an accident to declare it as const.
>
> NAK - the const is very valid here, as the v2 interface (as opposed
> to the v1 one) does _not_ modify this array (or if it does, it's a
> bug). This is a guarantee made to user mode, so it should also be
> expressed that way in the interface.
>
> But of course the cast used before this patch isn't right either, as
> it indeed inappropriately discards the qualifier. Afaiu this was done
> to simplify the internal workings of the code, but I don't think it's
> desirable to sacrifice type safety for implementation simplicity.
m.arr here isn't const as m is really the V1 structure where m.arr is
non-const.
David
WARNING: multiple messages have this Message-ID (diff)
From: David Vrabel <david.vrabel@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
xen-devel@lists.xensource.com,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Andres Lagar-Cavilla <andreslc@gridcentric.ca>,
kernel-janitors@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Dan Carpenter <dan.carpenter@oracle.com>
Subject: Re: [patch 3/3] xen/privcmd: remove const modifier from declaration
Date: Mon, 10 Sep 2012 11:43:19 +0100 [thread overview]
Message-ID: <504DC447.9010301@citrix.com> (raw)
In-Reply-To: <504DC8FE020000780009A190@nat28.tlf.novell.com>
On 10/09/12 10:03, Jan Beulich wrote:
>>>> On 08.09.12 at 11:58, Dan Carpenter <dan.carpenter@oracle.com> wrote:
>> When we use this pointer, we cast away the const modifier and modify the
>> data. I think it was an accident to declare it as const.
>
> NAK - the const is very valid here, as the v2 interface (as opposed
> to the v1 one) does _not_ modify this array (or if it does, it's a
> bug). This is a guarantee made to user mode, so it should also be
> expressed that way in the interface.
>
> But of course the cast used before this patch isn't right either, as
> it indeed inappropriately discards the qualifier. Afaiu this was done
> to simplify the internal workings of the code, but I don't think it's
> desirable to sacrifice type safety for implementation simplicity.
m.arr here isn't const as m is really the V1 structure where m.arr is
non-const.
David
next prev parent reply other threads:[~2012-09-10 10:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-08 9:58 [patch 3/3] xen/privcmd: remove const modifier from declaration Dan Carpenter
2012-09-08 9:58 ` Dan Carpenter
2012-09-09 19:50 ` Andres Lagar-Cavilla
2012-09-09 19:50 ` Andres Lagar-Cavilla
2012-09-09 19:50 ` Andres Lagar-Cavilla
2012-09-10 9:03 ` [Xen-devel] " Jan Beulich
2012-09-10 9:03 ` Jan Beulich
2012-09-10 9:03 ` Jan Beulich
2012-09-10 10:21 ` [patch 3/3 v2] xen/privcmd: add a __user annotation to a cast Dan Carpenter
2012-09-10 10:21 ` Dan Carpenter
2012-09-10 10:43 ` David Vrabel [this message]
2012-09-10 10:43 ` [patch 3/3] xen/privcmd: remove const modifier from declaration David Vrabel
2012-09-10 10:43 ` [Xen-devel] " David Vrabel
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