From: Jan Beulich <jbeulich@suse.com>
To: Julien Grall <julien@xen.org>
Cc: iwj@xenproject.org, wl@xen.org, andrew.cooper3@citrix.com,
george.dunlap@citrix.com, sstabellini@kernel.org,
jgross@suse.com, christian.lindig@citrix.com, dave@recoil.org,
xen-devel@lists.xenproject.org,
Igor Druzhinin <igor.druzhinin@citrix.com>
Subject: Re: [PATCH] tools/libxc: use uint32_t for pirq in xc_domain_irq_permission
Date: Wed, 7 Jul 2021 15:14:23 +0200 [thread overview]
Message-ID: <e2def3e5-8e00-8b52-2d0f-5231963607ee@suse.com> (raw)
In-Reply-To: <927c1c59-734a-4013-9286-137fd7026c26@xen.org>
On 07.07.2021 14:59, Julien Grall wrote:
> On 07/07/2021 13:54, Jan Beulich wrote:
>> On 07.07.2021 14:51, Julien Grall wrote:
>>> On 07/07/2021 02:02, Igor Druzhinin wrote:
>>>> Current unit8_t for pirq argument in this interface is too restrictive
>>>> causing failures on modern hardware with lots of GSIs. That extends down to
>>>> XEN_DOMCTL_irq_permission ABI structure where it needs to be fixed up
>>>> as well. Internal Xen structures appear to be fine. Existing users of
>>>> the interface in tree (libxl, ocaml and python bindings) are already using
>>>> int for pirq representation that should be wide enough.
>>>
>>> By "int", I am assuming you imply "signed int", is that correct?
>>>
>>> If so, should the function xc_domain_irq_permission() interface take an
>>> int in parameter and check it is not negative?
>>
>> Please let's not make things worse than they are, the more that
>
> Well, what I am trying to prevent is surprise where the caller
> mistakenly pass a negative value that will be interpreted as a positive
> value...
This happens all the time when converting from signed to unsigned
perhaps just internally.
> Such issues are beyong annoying to debug...
No worse than any other out-of-bounds value, I would say.
> > ./CODING_STYLE is unambiguous in cases like this one.
>
> Hmmm... The coding style mention the fixed size but nothing about the
> signedness of the type...
Oh, sorry, yes. The adjustment for this even pre-dates the two
patches to ./CODING_STYLE that I've on record as pending for
nearly two years.
> The alternative suggestion is to keep a unsigned type but check the bit
> 31 is not set.
Why? Why not bit 30 or bit 27? There's nothing special about
bit 31 in an unsigned number. You'll get an error from the
underlying hypercall for any out of bounds values, not just
ones with bit 31, 30, or 27 set.
Jan
next prev parent reply other threads:[~2021-07-07 13:14 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-07 1:02 [PATCH] tools/libxc: use uint32_t for pirq in xc_domain_irq_permission Igor Druzhinin
2021-07-07 7:46 ` Jan Beulich
2021-07-07 9:19 ` Andrew Cooper
2021-07-08 1:08 ` Igor Druzhinin
2021-07-08 1:11 ` Andrew Cooper
2021-07-08 1:14 ` Igor Druzhinin
2021-07-08 1:26 ` Andrew Cooper
2021-07-08 1:30 ` Igor Druzhinin
2021-07-07 8:48 ` Christian Lindig
2021-07-07 12:51 ` Julien Grall
2021-07-07 12:54 ` Jan Beulich
2021-07-07 12:59 ` Julien Grall
2021-07-07 13:14 ` Jan Beulich [this message]
2021-07-07 13:21 ` Julien Grall
2021-07-07 13:25 ` Jan Beulich
2021-07-08 2:06 ` Igor Druzhinin
2021-07-12 8:59 ` Julien Grall
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=e2def3e5-8e00-8b52-2d0f-5231963607ee@suse.com \
--to=jbeulich@suse.com \
--cc=andrew.cooper3@citrix.com \
--cc=christian.lindig@citrix.com \
--cc=dave@recoil.org \
--cc=george.dunlap@citrix.com \
--cc=igor.druzhinin@citrix.com \
--cc=iwj@xenproject.org \
--cc=jgross@suse.com \
--cc=julien@xen.org \
--cc=sstabellini@kernel.org \
--cc=wl@xen.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).