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From: Stephen Hemminger <stephen@networkplumber.org>
To: Atzm Watanabe <atzm@stratosphere.co.jp>
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH] packet: Deliver VLAN TPID to userspace
Date: Fri, 18 Oct 2013 10:56:55 -0700	[thread overview]
Message-ID: <20131018105655.2cdc628e@nehalam.linuxnetplumber.net> (raw)
In-Reply-To: <87a9i6jymc.wl%atzm@stratosphere.co.jp>

On Sat, 19 Oct 2013 02:08:11 +0900
Atzm Watanabe <atzm@stratosphere.co.jp> wrote:

> diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h
> index dbf0666..6e36e0a 100644
> --- a/include/uapi/linux/if_packet.h
> +++ b/include/uapi/linux/if_packet.h
> @@ -83,7 +83,7 @@ struct tpacket_auxdata {
>  	__u16		tp_mac;
>  	__u16		tp_net;
>  	__u16		tp_vlan_tci;
> -	__u16		tp_padding;
> +	__u16		tp_vlan_tpid;
>  };
>  
>  /* Rx ring - header status */
> @@ -132,12 +132,13 @@ struct tpacket2_hdr {
>  	__u32		tp_sec;
>  	__u32		tp_nsec;
>  	__u16		tp_vlan_tci;
> -	__u16		tp_padding;
> +	__u16		tp_vlan_tpid;
>  };
>  
>  struct tpacket_hdr_variant1 {
>  	__u32	tp_rxhash;
>  	__u32	tp_vlan_tci;
> +	__u32	tp_vlan_tpid;
>  };

The last change will break ABI to userspace applications.
You can reuse padding elements; but you can't increase (or shrink)
an existing structure.

  reply	other threads:[~2013-10-18 17:57 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-18 17:08 [PATCH] packet: Deliver VLAN TPID to userspace Atzm Watanabe
2013-10-18 17:56 ` Stephen Hemminger [this message]
2013-10-19  6:19   ` Atzm Watanabe
2013-10-21  9:24     ` Ben Hutchings
2013-10-22  2:56       ` Atzm Watanabe
2013-10-22 22:41         ` Stephen Hemminger
2013-10-23  6:51           ` Atzm Watanabe

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