From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8953BC433F5 for ; Mon, 3 Jan 2022 14:40:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234429AbiACOk4 (ORCPT ); Mon, 3 Jan 2022 09:40:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234969AbiACOid (ORCPT ); Mon, 3 Jan 2022 09:38:33 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 53A72C07E5C3; Mon, 3 Jan 2022 06:34:17 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 1C946B80EFC; Mon, 3 Jan 2022 14:34:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E251C36AED; Mon, 3 Jan 2022 14:34:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1641220454; bh=k7D1OA2Ii3MGEVnnuFmG31cfWeIt3MzNwOsJB+Rl5u4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KYtQWz/AXroLr2Vsl7cRBhYO79kVmnklB5urksX1ChFPqV3U9XjIKjEXsflmph/+k 3g7yuwwnIYswgO3hDkjO79s/ufo0xZ9fLquPXsNCLF0y06wimbfj1pzODP6Qxcx9YD 9e5wKVFfjjjYylyXjmuVXpizQa77DjlCGiMdoCdY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Matthias-Christian Ott , Andrew Lunn , "David S. Miller" , Sasha Levin Subject: [PATCH 5.15 31/73] net: usb: pegasus: Do not drop long Ethernet frames Date: Mon, 3 Jan 2022 15:23:52 +0100 Message-Id: <20220103142057.914920766@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220103142056.911344037@linuxfoundation.org> References: <20220103142056.911344037@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Matthias-Christian Ott [ Upstream commit ca506fca461b260ab32952b610c3d4aadc6c11fd ] The D-Link DSB-650TX (2001:4002) is unable to receive Ethernet frames that are longer than 1518 octets, for example, Ethernet frames that contain 802.1Q VLAN tags. The frames are sent to the pegasus driver via USB but the driver discards them because they have the Long_pkt field set to 1 in the received status report. The function read_bulk_callback of the pegasus driver treats such received "packets" (in the terminology of the hardware) as errors but the field simply does just indicate that the Ethernet frame (MAC destination to FCS) is longer than 1518 octets. It seems that in the 1990s there was a distinction between "giant" (> 1518) and "runt" (< 64) frames and the hardware includes flags to indicate this distinction. It seems that the purpose of the distinction "giant" frames was to not allow infinitely long frames due to transmission errors and to allow hardware to have an upper limit of the frame size. However, the hardware already has such limit with its 2048 octet receive buffer and, therefore, Long_pkt is merely a convention and should not be treated as a receive error. Actually, the hardware is even able to receive Ethernet frames with 2048 octets which exceeds the claimed limit frame size limit of the driver of 1536 octets (PEGASUS_MTU). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Matthias-Christian Ott Reviewed-by: Andrew Lunn Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/usb/pegasus.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/usb/pegasus.c b/drivers/net/usb/pegasus.c index 6a92a3fef75e5..cd063f45785b7 100644 --- a/drivers/net/usb/pegasus.c +++ b/drivers/net/usb/pegasus.c @@ -493,11 +493,11 @@ static void read_bulk_callback(struct urb *urb) goto goon; rx_status = buf[count - 2]; - if (rx_status & 0x1e) { + if (rx_status & 0x1c) { netif_dbg(pegasus, rx_err, net, "RX packet error %x\n", rx_status); net->stats.rx_errors++; - if (rx_status & 0x06) /* long or runt */ + if (rx_status & 0x04) /* runt */ net->stats.rx_length_errors++; if (rx_status & 0x08) net->stats.rx_crc_errors++; -- 2.34.1