From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH net-next] gro: should aggregate frames without DF Date: Fri, 31 May 2013 10:02:32 -0700 Message-ID: <1370019752.5109.108.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev , Jerry Chu , Herbert Xu To: David Miller Return-path: Received: from mail-pd0-f177.google.com ([209.85.192.177]:54959 "EHLO mail-pd0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751657Ab3EaRCe (ORCPT ); Fri, 31 May 2013 13:02:34 -0400 Received: by mail-pd0-f177.google.com with SMTP id u11so2511982pdi.36 for ; Fri, 31 May 2013 10:02:34 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet GRO on IPv4 doesn't aggregate frames if they don't have DF bit set. Some servers use IP_MTU_DISCOVER/IP_PMTUDISC_PROBE, so linux receivers are unable to aggregate this kind of traffic. The right thing to do is to allow aggregation as long as the DF bit has same value on all segments. bnx2x LRO does this correctly. Signed-off-by: Eric Dumazet Cc: Jerry Chu Cc: Herbert Xu --- net/ipv4/af_inet.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index b05ae96..328cc62 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -1384,9 +1384,9 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head, if (unlikely(ip_fast_csum((u8 *)iph, 5))) goto out_unlock; - id = ntohl(*(__be32 *)&iph->id); - flush = (u16)((ntohl(*(__be32 *)iph) ^ skb_gro_len(skb)) | (id ^ IP_DF)); - id >>= 16; + flush = ntohs(iph->tot_len) ^ skb_gro_len(skb); + + id = ntohs(iph->id); for (p = *head; p; p = p->next) { struct iphdr *iph2; @@ -1407,6 +1407,7 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head, NAPI_GRO_CB(p)->flush |= (iph->ttl ^ iph2->ttl) | (iph->tos ^ iph2->tos) | + ((iph->frag_off ^ iph2->frag_off) & htons(IP_DF)) | ((u16)(ntohs(iph2->id) + NAPI_GRO_CB(p)->count) ^ id); NAPI_GRO_CB(p)->flush |= flush;