netdev - Re: [PATCH v4 net 3/3] sctp: Perform software checksum if packet has to be fragmented.

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Message-ID: <20131016133431.GC10623@neilslaptop.think-freely.org>
Date:	Wed, 16 Oct 2013 09:34:31 -0400
From:	Neil Horman <nhorman@...driver.com>
To:	Vlad Yasevich <vyasevich@...il.com>
Cc:	netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
	fan.du@...driver.com
Subject: Re: [PATCH v4 net 3/3] sctp: Perform software checksum if packet has
 to be fragmented.

On Tue, Oct 15, 2013 at 10:01:31PM -0400, Vlad Yasevich wrote:
> IP/IPv6 fragmentation knows how to compute only TCP/UDP checksum.
> This causes problems if SCTP packets has to be fragmented and
> ipsummed has been set to PARTIAL due to checksum offload support.
> This condition can happen when retransmitting after MTU discover,
> or when INIT or other control chunks are larger then MTU.
> Check for the rare fragmentation condition in SCTP and use software
> checksum calculation in this case.
> 
> CC: Fan Du <fan.du@...driver.com>
> Signed-off-by: Vlad Yasevich <vyasevich@...il.com>
> ---
>  net/sctp/output.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/sctp/output.c b/net/sctp/output.c
> index d35b54c..3191373 100644
> --- a/net/sctp/output.c
> +++ b/net/sctp/output.c
> @@ -537,7 +537,7 @@ int sctp_packet_transmit(struct sctp_packet *packet)
>  	 */
>  	if (!sctp_checksum_disable) {
>  		if (!(dst->dev->features & NETIF_F_SCTP_CSUM) ||
> -		    (dst_xfrm(dst) != NULL)) {
> +		    (dst_xfrm(dst) != NULL) || packet->ipfragok) {
>  			__u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len);
>  
>  			/* 3) Put the resultant value into the checksum field in the
> -- 
> 1.8.3.1
> 
> --
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> 
Acked-by: Neil Horman <nhorman@...driver.com>

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