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 X-Spam-Level: X-Spam-Status: No, score=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10FA5C433ED for ; Sun, 11 Apr 2021 21:23:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3267610C8 for ; Sun, 11 Apr 2021 21:23:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235726AbhDKVXz (ORCPT ); Sun, 11 Apr 2021 17:23:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235338AbhDKVXw (ORCPT ); Sun, 11 Apr 2021 17:23:52 -0400 Received: from mail-yb1-xb2c.google.com (mail-yb1-xb2c.google.com [IPv6:2607:f8b0:4864:20::b2c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34651C061574 for ; Sun, 11 Apr 2021 14:23:33 -0700 (PDT) Received: by mail-yb1-xb2c.google.com with SMTP id z1so12825034ybf.6 for ; Sun, 11 Apr 2021 14:23:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=s6wkbqBA5jKWZN4q21yFCGp918hjP1L7ivFeYGjBOqQ=; b=Oa0ZMgio6Z9baxTPoSl6M1bPnIC/KoXwqmD93MdVLOcBNx76z186BfpzBKrkRFvqo1 VrdvVi8lEsMAN1ALzS5dRjHYuBfTLN3oSYELdmJg+TKlvVLhqSucgga/kFE1Oh0akApz XmbGwae/WmP2OoAiD6r/+tZoLAMk8y2QSDz1ilXs1MA6HPIGHMO7V0IV+GT3quS5qFSY l828/nm4v713WheizgsfWEnC6Xe6uYbWYLq0k8o9INX/dR+WtGg+Hp05XEDsnYgaAy/s 3C9XHeAghZ/fTtWMs7bowBTDnO8qpDwn987ZYgPC0I6e/XTz9Iv3NqqP2m/U682OWKE6 igrQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=s6wkbqBA5jKWZN4q21yFCGp918hjP1L7ivFeYGjBOqQ=; b=T6sCUDfcpjXS6d+6E31VodMLwgsqWLs/yc4jLqIG/r9AszPENmrQcj12HpYioq9ejR JDSXrz7rrEadTC3MJ0Tjz7+pf6G08CU2B2BE1fVi91DNIoqcNAYOWIzV0AgShZMr5Sle zc55yKVkK+EKy6ASKCvhrmCdGfNkAoLgsLGaJkPsOZQeWq8Btr1mAjgYVqg7XuGTNfvC GYy/WWjf1AeJw+3zoyu0go8b2Avn2gO61+s1DjuF+lfWuK35j13Ik6LhcFMHt8alBIrD ESik+qSyUyVOOXtt6eJWNUWC1cx3pb57/7foQYX3ikOTsI2y8vySCg6gvmMxcLMrCyEf lKNw== X-Gm-Message-State: AOAM533MticN5x3cDFCf86uHmd6jNiApLAPlKQrA5+uiKMfVWgaGXmZ2 T5IuT/6zBl+ConwwLtQEgUe4OYOLnJ75aOTLe23pHw== X-Google-Smtp-Source: ABdhPJxu+cegXOLCQP6ej753YV30YyK7KGcm6ddWduFIt3Nzk7J7ZQUUrWIBdXA3Xj16yXYHsaRk/MAcgAsLqO4qu80= X-Received: by 2002:a25:7e01:: with SMTP id z1mr35375662ybc.253.1618176212047; Sun, 11 Apr 2021 14:23:32 -0700 (PDT) MIME-Version: 1.0 References: <20210402132602.3659282-1-eric.dumazet@gmail.com> <20210411134329.GA132317@roeck-us.net> <0f63dc52-ea72-16b6-7dcd-efb24de0c852@roeck-us.net> In-Reply-To: <0f63dc52-ea72-16b6-7dcd-efb24de0c852@roeck-us.net> From: Eric Dumazet Date: Sun, 11 Apr 2021 23:23:20 +0200 Message-ID: Subject: Re: [PATCH net] virtio_net: Do not pull payload in skb->head To: Guenter Roeck Cc: Eric Dumazet , "David S . Miller" , Jakub Kicinski , netdev , Xuan Zhuo , "Michael S. Tsirkin" , Jason Wang , virtualization@lists.linux-foundation.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Sun, Apr 11, 2021 at 10:37 PM Guenter Roeck wrote: > > On 4/11/21 8:06 AM, Eric Dumazet wrote: > > On Sun, Apr 11, 2021 at 3:43 PM Guenter Roeck wrote: > > > >> This patch causes a virtio-net interface failure when booting sh4 images > >> in qemu. The test case is nothing special: Just try to get an IP address > >> using udhcpc. If it fails, udhcpc reports: > >> > >> udhcpc: started, v1.33.0 > >> udhcpc: sending discover > >> FAIL > >> > > > > Can you investigate where the incoming packet is dropped ? > > > > Unless I am missing something, packets are not dropped. It looks more > like udhcpc gets bad indigestion in the receive path and exits immediately. > Plus, it doesn't happen all the time; sometimes it receives the discover > response and is able to obtain an IP address. > > Overall this is quite puzzling since udhcpc exits immediately when the problem > is seen, no matter which option I give it on the command line; it should not > really do that. Could you strace both cases and report differences you can spot ? strace -o STRACE -f -s 1000 udhcpc