Date: Tue, 9 Feb 2010 10:05:10 -0800 From: "Li, Qing" <qing.li@bluecoat.com> To: "M. Warner Losh" <imp@bsdimp.com>, <net@freebsd.org> Subject: RE: struct sockaddr * and alignment Message-ID: <B583FBF374231F4A89607B4D08578A43046737A7@bcs-mail03.internal.cacheflow.com> References: <20100209.103411.506052712871889475.imp@bsdimp.com>
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>
> Sure enough, that fixes this warning. Yea. But, sadly, it causes
> other problems. If you look at sbin/atm/atmconfig/natm.c you'll see
> code like:
>=20
> static void
> store_route(struct rt_msghdr *rtm)
> {
> ...
> char *cp
> struct sockaddr *sa;
> ...
>=20
> cp =3D (char *)(rtm + 1);
> ...
> sa =3D (struct sockaddr *)cp;
> cp +=3D roundup(sa->sa_len, sizeof(long));
> ...
>=20
> which breaks because we're now casting from an __aligned(1) char * to
> an __aligned(8) sockaddr *.
> And it is only rounding the size of the structure to long, rather than
> int64 like sockaddr_storage suggests is the proper alignment. But I
> haven't looked in the kernel to see if there's an issue there with
> routing sockets or not.
>=20
In the kernel route.h, the macro SA_SIZE is used by the routing socket
code and may the root of the problem.
-- Qing
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