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From: Changli Gao <xiaosuo@gmail.com>
Date: Mon, 23 Aug 2010 10:29:49 +0800
Message-ID: <AANLkTikBcuYa_HNzhYYG62CLjcfptQNQM_zOsv9fXRfS@mail.gmail.com>
Subject: Re: [PATCH] net: define __packed for the userspace code
To: David Miller <davem@davemloft.net>
Cc: arnd@arndb.de, eric.dumazet@gmail.com, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
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On Mon, Aug 23, 2010 at 9:36 AM, David Miller <davem@davemloft.net> wrote:
>
> I don't think this it the reason it was being used here.
>
> Any, for one thing, we definitely cannot remove the existing packed
> markers or else we will break every single userland tool out there
> using these socket address structures.
>
> Even the first two members (sa_family_t and unsigned int) will be
> positioned differently if we remove the marker.
>
> I suspect the packed attribute is there to make sure the pppo* socket
> address structures fit within the generic socket address object size.
> (see struct __kernel_sockaddr_storage and struct sockaddr).
>
> As to the problem at-hand, I think we need to use __attribute__((packed))
> here. ?And that's what I'll commit into net-2.6 and net-next-2.6
>

Do you mean that use the __attribute__((packed)) annotation in all of
these files:

localhost linux # grep "\<__packed\>" usr/include/ -r | uniq
usr/include/linux/if_hippi.h:} __packed;
usr/include/linux/if_fddi.h:} __packed;
usr/include/linux/nbd.h:} __packed;
usr/include/linux/ncp.h:} __packed;
usr/include/linux/rfkill.h:} __packed;
usr/include/linux/if_pppox.h:} __packed;
usr/include/linux/phonet.h:} __packed;
usr/include/linux/ipv6.h:} __packed;    /* required for some archs */
usr/include/linux/ipv6.h:} __packed;
usr/include/linux/if_ether.h:} __packed;

-- 
Regards,
Changli Gao(xiaosuo@gmail.com)
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