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[2620:137:e000::3:2]) by mx.google.com with ESMTPS id b190-20020a62cfc7000000b006c0fe2dfec1si189300pfg.72.2023.10.31.14.22.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Oct 2023 14:22:47 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:2 as permitted sender) client-ip=2620:137:e000::3:2; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=VFXVbVmt; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:2 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by agentk.vger.email (Postfix) with ESMTP id 53FA3802EE6E; Tue, 31 Oct 2023 14:22:43 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at agentk.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231975AbjJaVWZ (ORCPT + 99 others); Tue, 31 Oct 2023 17:22:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229649AbjJaVWY (ORCPT ); Tue, 31 Oct 2023 17:22:24 -0400 Received: from mail-yw1-x1130.google.com (mail-yw1-x1130.google.com [IPv6:2607:f8b0:4864:20::1130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2D3D1B4 for ; Tue, 31 Oct 2023 14:22:19 -0700 (PDT) Received: by mail-yw1-x1130.google.com with SMTP id 00721157ae682-5a8ada42c2aso61794707b3.3 for ; Tue, 31 Oct 2023 14:22:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1698787338; x=1699392138; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=n4LrpsRV8LqgOH/k11ky5xw4VxQr9Kt5ptUpPAKGLd4=; b=VFXVbVmtEsAduIFm3C29S4LWKF0Zzc/9w1eewDJR5FUooAQ97/+HYMmj+DjFAgKmra oyYmj4MHlTeuW4I4IjJ+YYth+Vz9JIuoKfGK6qBTD/W2CegX+aZ2LZTZJwkKHu/KcxDr qR/O1ySVIS2FVcE79M9baNFnSoly3Ko1SJw9rhtChiYliKGSNvpHxdoiJ9c4FzENqBAL 09H+D5O2HotBad004luMTw6yStgkL+Zge4c8PaDEjwRCqr8tl3qHvzzjnd1B7mMnTAn4 n9/c16oLwQ0fMzAT5tJmW+5BS/G7kNwQNWNZ6flH4rpOZbXzPnbVjIm2Ly/FPHQr757c 1PGg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698787338; x=1699392138; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=n4LrpsRV8LqgOH/k11ky5xw4VxQr9Kt5ptUpPAKGLd4=; b=xJnvgPp0tkbKMluFzk1wwu+IWTQLWA2gBMpg/dhbqgfrv75rmd2uLvhT4+C4fc+kls R5v4ms2pMn0Zq44fSKvauV3ApI+t6IPUnDx+NFo0YUtgA8RdBq5oxeAKAvbnY/FwNznB m0cSGBCuy/tDCaJvqmLHKjS2DpNiVfUt+na697McHAq2njLDzYtkRrizKU/Wmstnq2Hg 5WrgLY0Jsji5KxDkbksmqi9vOa8cYAJMpJUzQyN0AF3wqb6Qb4lsVSyCJpCHCnv24LfD pmwJZ79WXKStU+drSmN9b/CXpY3BbYUh1HCSWIYcj62Md4qtlNkv4lNGZFZYlSGCJNaL iwTQ== X-Gm-Message-State: AOJu0Yys7OZIxzy7U5ffPQq2wkIsoP5L/2B/bpUIX55SfJQZIGC9h6+P JvrDJ8MZMFGGNoawuHYEDABd6VHLM1TeA6eE7ORrMw== X-Received: by 2002:a81:c704:0:b0:5a7:b81a:7f5d with SMTP id m4-20020a81c704000000b005a7b81a7f5dmr13974357ywi.18.1698787338056; Tue, 31 Oct 2023 14:22:18 -0700 (PDT) MIME-Version: 1.0 References: <20231030-fix-rtl8366rb-v2-1-e66e1ef7dbd2@linaro.org> <20231030141623.ufzhb4ttvxi3ukbj@skbuf> <20231030152325.qdpvv4nbczhal35c@skbuf> <20231030153057.3ofydbzh7q2um3os@skbuf> In-Reply-To: <20231030153057.3ofydbzh7q2um3os@skbuf> From: Linus Walleij Date: Tue, 31 Oct 2023 22:22:05 +0100 Message-ID: Subject: Re: [PATCH net v2] net: dsa: tag_rtl4_a: Bump min packet size To: Vladimir Oltean Cc: Andrew Lunn , Florian Fainelli , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on agentk.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (agentk.vger.email [0.0.0.0]); Tue, 31 Oct 2023 14:22:43 -0700 (PDT) Hi Vladimir, I got around to testing this too: On Mon, Oct 30, 2023 at 4:31=E2=80=AFPM Vladimir Oltean = wrote: > Could you please place these skb_dump() calls before and after the magic > __skb_put_padto() call, for us to see if anything unexpected changes? > Maybe the socket buffers have some unusual geometry which the conduit > interface doesn't like, for some reason. > > The number of skb dumps that you provide back should be even, and > ideally the first one should be the unaltered packet, to avoid confusion = :) I did a variant to just get one SKB dump and not tons of them; @@ -37,22 +37,35 @@ static struct sk_buff *rtl4a_tag_xmit(struct sk_buff *s= kb, struct net_device *dev) { struct dsa_port *dp =3D dsa_slave_to_port(dev); + static int cnt =3D 0; __be16 *p; u8 *tag; u16 out; - /* Pad out to at least 60 bytes */ - if (unlikely(__skb_put_padto(skb, ETH_ZLEN, false))) - return NULL; - /* Packets over 1496 bytes get dropped unless they get padded * out to 1518 bytes. 1496 is ETH_DATA_LEN - tag which is hardly * a coinicidence, and 1518 is ETH_FRAME_LEN + FCS so we define * the threshold size and padding like this. */ if (skb->len >=3D (ETH_DATA_LEN - RTL4_A_HDR_LEN)) { + cnt++; + + if (cnt =3D=3D 1) { + pr_info("SKB before padding:\n"); + skb_dump(KERN_INFO, skb, true); + } + if (unlikely(__skb_put_padto(skb, ETH_FRAME_LEN + ETH_FCS_LEN, false))) return NULL; + + if (cnt =3D=3D 1) { + pr_info("SKB after padding:\n"); + skb_dump(KERN_INFO, skb, true); + } + } else { + /* Pad out to at least 60 bytes */ + if (unlikely(__skb_put_padto(skb, ETH_ZLEN, false))) + return NULL; } # ping -s 1472 192.168.1.137 The result: SKB before padding: 37 (192.168.1.13skb len=3D1514 headroom=3D18 headlen=3D1514 tailroom=3D260 mac=3D(18,14) net=3D(32,20) trans=3D52 shinfo(txflags=3D0 nr_frags=3D0 gso(size=3D0 type=3D0 segs=3D0)) csum(0xd4ef2b1 ip_summed=3D0 complete_sw=3D0 valid=3D0 level=3D0) hash(0x0 sw=3D0 l4=3D0) proto=3D0x0800 pkttype=3D0 iif=3D0 7): 1472 data bydev name=3Dlan0 feat=3D0x0002000000005020 tes sk family=3D2 type=3D3 proto=3D1 skb headroom: 00000000: 00 02 00 01 00 00 00 00 00 00 03 78 02 00 bc ae skb headroom: 00000010: 00 00 skb linear: 00000000: bc ae c5 6b a8 3d c2 2f 0b dc cc b4 08 00 45 00 skb linear: 00000010: 05 dc 3b de 40 00 40 01 75 68 c0 a8 01 01 c0 a8 skb linear: 00000020: 01 89 08 00 16 d2 09 54 00 00 8a cc 4d 0d 00 00 skb linear: 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000210: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000220: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000230: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000240: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000250: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000260: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000270: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000290: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000310: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000320: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000330: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000340: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000350: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000360: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000370: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000390: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000410: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000420: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000430: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000440: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000450: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000460: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000470: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000490: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000510: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000520: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000530: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000540: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000550: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000560: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000570: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000590: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000005a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000005b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000005c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000005d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000005e0: 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000100: 00 00 00 00 SKB after padding: skb len=3D1518 headroom=3D18 headlen=3D1518 tailroom=3D256 mac=3D(18,14) net=3D(32,20) trans=3D52 shinfo(txflags=3D0 nr_frags=3D0 gso(size=3D0 type=3D0 segs=3D0)) csum(0xd4ef2b1 ip_summed=3D0 complete_sw=3D0 valid=3D0 level=3D0) hash(0x0 sw=3D0 l4=3D0) proto=3D0x0800 pkttype=3D0 iif=3D0 dev name=3Dlan0 feat=3D0x0002000000005020 sk family=3D2 type=3D3 proto=3D1 skb headroom: 00000000: 00 02 00 01 00 00 00 00 00 00 03 78 02 00 bc ae skb headroom: 00000010: 00 00 skb linear: 00000000: bc ae c5 6b a8 3d c2 2f 0b dc cc b4 08 00 45 00 skb linear: 00000010: 05 dc 3b de 40 00 40 01 75 68 c0 a8 01 01 c0 a8 skb linear: 00000020: 01 89 08 00 16 d2 09 54 00 00 8a cc 4d 0d 00 00 skb linear: 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000140: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000150: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000001f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000210: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000220: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000230: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000240: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000250: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000260: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000270: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000290: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000002f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000310: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000320: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000330: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000340: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000350: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000360: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000370: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000390: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000003f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000410: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000420: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000430: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000440: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000450: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000460: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000470: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000490: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000004f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000510: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000520: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000530: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000540: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000550: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000560: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000570: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 00000590: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000005a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000005b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000005c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000005d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb linear: 000005e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 00000090: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 skb tailroom: 000000f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 As expected the linear SKB is 4 bytes longer in this case. Yours, Linus Walleij