From: Nicolas Dichtel <nicolas.dichtel@6wind•com>
To: Ben Hutchings <bhutchings@solarflare•com>
Cc: tgraf@suug•ch, netdev@vger•kernel.org, davem@davemloft•net,
David.Laight@ACULAB•COM
Subject: Re: [PATCH] netlink: align attributes on 64-bits
Date: Fri, 14 Dec 2012 17:04:01 +0100 [thread overview]
Message-ID: <50CB4DF1.5020903@6wind.com> (raw)
In-Reply-To: <1355500160.2626.9.camel@bwh-desktop.uk.solarflarecom.com>
Le 14/12/2012 16:49, Ben Hutchings a écrit :
> On Fri, 2012-12-14 at 14:16 +0100, Nicolas Dichtel wrote:
>> On 64 bits arch, we must ensure that attributes are always aligned on 64-bits
>> boundary. We do that by adding attributes of type 0, size 4 (alignment on
>> 32-bits is already done) when needed. Attribute type 0 should be available and
>> unused in all netlink families.
> [...]
>> --- a/lib/nlattr.c
>> +++ b/lib/nlattr.c
>> @@ -450,9 +450,18 @@ EXPORT_SYMBOL(__nla_put_nohdr);
>> */
>> int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)
>> {
>> - if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))
>> + int align = IS_ALIGNED((unsigned long)skb_tail_pointer(skb), sizeof(void *)) ? 0 : 4;
>
> The assumption here is that nothing needs to be aligned to a greater
> width than that of a pointer. However, for most 32-bit architectures
> (i386 being an exception) the C ABI requires 64-bit alignment for 64-bit
> types. There may be cases where a mostly 32-bit processor really
> requires 64-bit alignment, e.g. to load or save a pair of registers.
Ok, I will wait other comments to send a v2 (which will align these attributes
for all arch).
Nicolas
next prev parent reply other threads:[~2012-12-14 16:04 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-04 11:13 [PATCH net-next 0/7] Allow to monitor multicast cache event via rtnetlink Nicolas Dichtel
2012-12-04 11:13 ` [PATCH net-next 1/7] netconf: advertise mc_forwarding status Nicolas Dichtel
2012-12-04 11:13 ` [PATCH net-next 2/7] ip6mr: use nla_nest_* helpers Nicolas Dichtel
2012-12-04 11:13 ` [PATCH net-next 3/7] ipmr/ip6mr: advertise mfc stats via rtnetlink Nicolas Dichtel
2012-12-04 11:13 ` [PATCH net-next 4/7] ipmr/ip6mr: report origin of mfc entry into rtnl msg Nicolas Dichtel
2012-12-04 11:13 ` [PATCH net-next 5/7] ipmr/ip6mr: allow to get unresolved cache via netlink Nicolas Dichtel
2012-12-04 11:13 ` [PATCH net-next 6/7] ipmr: advertise new mfc entries via rtnl Nicolas Dichtel
2012-12-04 11:13 ` [PATCH net-next 7/7] ip6mr: " Nicolas Dichtel
2012-12-04 18:09 ` [PATCH net-next 0/7] Allow to monitor multicast cache event via rtnetlink David Miller
2012-12-04 20:02 ` Nicolas Dichtel
2012-12-05 11:02 ` Nicolas Dichtel
2012-12-05 11:41 ` David Laight
2012-12-05 17:54 ` David Miller
2012-12-06 8:43 ` Nicolas Dichtel
2012-12-06 17:49 ` Thomas Graf
2012-12-06 21:49 ` Nicolas Dichtel
2012-12-07 10:38 ` David Laight
2012-12-07 10:58 ` Thomas Graf
2012-12-11 15:03 ` Nicolas Dichtel
2012-12-11 18:40 ` Thomas Graf
2012-12-12 17:30 ` Nicolas Dichtel
2012-12-14 13:16 ` [PATCH] netlink: align attributes on 64-bits Nicolas Dichtel
2012-12-14 15:49 ` Ben Hutchings
2012-12-14 16:04 ` Nicolas Dichtel [this message]
2012-12-17 16:49 ` [PATCH v2] " Nicolas Dichtel
2012-12-17 17:06 ` David Laight
2012-12-17 17:35 ` Nicolas Dichtel
2012-12-18 9:19 ` David Laight
2012-12-18 10:18 ` Nicolas Dichtel
2012-12-18 12:57 ` Thomas Graf
2012-12-18 16:23 ` Nicolas Dichtel
2012-12-18 16:50 ` David Laight
2012-12-18 17:11 ` Thomas Graf
2012-12-19 9:17 ` David Laight
2012-12-19 17:20 ` Thomas Graf
2012-12-20 9:37 ` David Laight
2012-12-20 9:40 ` David Laight
2012-12-18 17:08 ` Thomas Graf
2012-12-18 22:07 ` Nicolas Dichtel
2012-12-19 11:22 ` Nicolas Dichtel
2012-12-19 17:09 ` Thomas Graf
2012-12-19 18:07 ` Nicolas Dichtel
2012-12-17 9:59 ` [PATCH] " David Laight
2012-12-17 16:53 ` Nicolas Dichtel
2012-12-05 17:53 ` [PATCH net-next 0/7] Allow to monitor multicast cache event via rtnetlink David Miller
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=50CB4DF1.5020903@6wind.com \
--to=nicolas.dichtel@6wind$(echo .)com \
--cc=David.Laight@ACULAB$(echo .)COM \
--cc=bhutchings@solarflare$(echo .)com \
--cc=davem@davemloft$(echo .)net \
--cc=netdev@vger$(echo .)kernel.org \
--cc=tgraf@suug$(echo .)ch \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
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