From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Turull Subject: [PATCH net-next-2.6] pktgen: bug fix in transmission headers with frags=0 Date: Mon, 14 Mar 2011 15:31:00 +0100 Message-ID: <4D7E26A4.2070802@gmail.com> References: <4D7E167E.2090807@gmail.com> <1300110977.3423.16.camel@edumazet-laptop> <4D7E22A5.1000708@gmail.com> <1300112338.3423.27.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, Robert Olsson , Jens Laas , Voravit Tanyingyong To: Eric Dumazet Return-path: Received: from mail-fx0-f46.google.com ([209.85.161.46]:38661 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756028Ab1CNObl (ORCPT ); Mon, 14 Mar 2011 10:31:41 -0400 Received: by fxm17 with SMTP id 17so2948240fxm.19 for ; Mon, 14 Mar 2011 07:31:39 -0700 (PDT) In-Reply-To: <1300112338.3423.27.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: (bug introduced by commit 26ad787962ef84677a48c560 (pktgen: speedup fragmented skbs) The headers of pktgen were incorrectly added in a pktgen packet without frags (frags=0). There was an offset in the pktgen headers. The cause was in reusing the pgh variable as a return variable in skb_put when adding the payload to the skb. Signed-off-by: Daniel Turull --- The PKTGEN magic (be9b e955) now starts in the correct offset. Before the patch, it was starting with an offset of +16 bytes (sizeof(struct pktgen_hdr)) (be9b) Capture from tcpdump: before patch: 14:57:37.854812 IP 10.0.0.2.discard > 10.254.254.84.discard: UDP, length 18 0x0000: 001b 2157 ed84 001b 215d 01d0 0800 4500 0x0010: 002e 0004 0000 2011 8767 0a00 0002 0afe 0x0020: fe54 0009 0009 001a 0000 0000 0000 b072 0x0030: 9102 00ea ffff 0010 0000 be9b after patch: 14:44:32.896048 IP 10.0.0.2.discard > 10.217.234.56.discard: UDP, length 18 0x0000: 001b 2157 ed84 001b 215d 01d0 0800 4500 0x0010: 002e 0000 0000 2011 9bac 0a00 0002 0ad9 0x0020: ea38 0009 0009 001a 0000 be9b e955 0000 0x0030: 0001 4d7e 1b09 0005 5f23 af00 --- diff --git a/net/core/pktgen.c b/net/core/pktgen.c index f0aec6c..0c55eaa 100644 --- a/net/core/pktgen.c +++ b/net/core/pktgen.c @@ -2620,8 +2620,7 @@ static void pktgen_finalize_skb(struct pktgen_dev *pkt_dev, struct sk_buff *skb, datalen -= sizeof(*pgh); if (pkt_dev->nfrags <= 0) { - pgh = (struct pktgen_hdr *)skb_put(skb, datalen); - memset(pgh + 1, 0, datalen); + memset(skb_put(skb, datalen), 0, datalen); } else { int frags = pkt_dev->nfrags; int i, len;