From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: [PATCH net-next 2/2] include/uapi/linux/xfrm.h: Pack struct xfrm_usersa_info Date: Wed, 8 Jan 2014 20:33:03 +0000 Message-ID: <1389213183.1644.31.camel@bwh-desktop.uk.level5networks.com> References: <1389077339-12814-1-git-send-email-fan.du@windriver.com> <1389077339-12814-3-git-send-email-fan.du@windriver.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: , , , , To: Fan Du Return-path: Received: from webmail.solarflare.com ([12.187.104.25]:17093 "EHLO webmail.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757382AbaAHUdI (ORCPT ); Wed, 8 Jan 2014 15:33:08 -0500 In-Reply-To: <1389077339-12814-3-git-send-email-fan.du@windriver.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 2014-01-07 at 14:48 +0800, Fan Du wrote: > Otherwise 64bits kernel has sizeof(struct xfrm_usersa_info) 224 bytes, > while 32bits compiled iproute2 see the same structure as 220 bytes, which > leading deficit xfrm sa, in turn broken IPsec connectivity. > > Fix this by packing the structure. > > Signed-off-by: Fan Du > --- > include/uapi/linux/xfrm.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h > index 470bfae..61460c4 100644 > --- a/include/uapi/linux/xfrm.h > +++ b/include/uapi/linux/xfrm.h > @@ -366,7 +366,7 @@ struct xfrm_usersa_info { > #define XFRM_STATE_AF_UNSPEC 32 > #define XFRM_STATE_ALIGN4 64 > #define XFRM_STATE_ESN 128 > -}; > +} __attribute__((packed)); > > #define XFRM_SA_XFLAG_DONT_ENCAP_DSCP 1 > That change will make access to the structure very slow on some architectures, and I suspect it will cause other compatibility problems. I think the right thing to do is to reduce the minimum length of the structure in the netlink policy so that padding at the end is not required. (It looks like all field offsets will be the same on all 32/64-bit architecture pairs and there is only a differing amount of padding at the end of the structure for 32/64-bit alignment.) Ben. -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.