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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 36ED4C43387 for ; Fri, 18 Jan 2019 03:50:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F0D520850 for ; Fri, 18 Jan 2019 03:50:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726948AbfARDu2 (ORCPT ); Thu, 17 Jan 2019 22:50:28 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51386 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726716AbfARDu2 (ORCPT ); Thu, 17 Jan 2019 22:50:28 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 105773E7DF; Fri, 18 Jan 2019 03:50:28 +0000 (UTC) Received: from [10.72.12.162] (ovpn-12-162.pek2.redhat.com [10.72.12.162]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DD0B3101963A; Fri, 18 Jan 2019 03:50:21 +0000 (UTC) Subject: Re: [PATCH net 2/7] virtio_net: Don't call free_old_xmit_skbs for xdp_frames To: Toshiaki Makita , "David S. Miller" , "Michael S. Tsirkin" Cc: netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, Willem de Bruijn References: <1547724045-2726-1-git-send-email-makita.toshiaki@lab.ntt.co.jp> <1547724045-2726-3-git-send-email-makita.toshiaki@lab.ntt.co.jp> <7c8955f5-cd38-c26f-9932-0aa0be573b4e@redhat.com> <8b097123-5e10-69dd-a638-65e4dc6d7882@lab.ntt.co.jp> From: Jason Wang Message-ID: <0c6144fa-1e2c-4a50-c238-5c7f53672a25@redhat.com> Date: Fri, 18 Jan 2019 11:50:17 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <8b097123-5e10-69dd-a638-65e4dc6d7882@lab.ntt.co.jp> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Fri, 18 Jan 2019 03:50:28 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2019/1/18 上午9:44, Toshiaki Makita wrote: > On 2019/01/17 21:39, Jason Wang wrote: >> On 2019/1/17 下午7:20, Toshiaki Makita wrote: >>> When napi_tx is enabled, virtnet_poll_cleantx() called >>> free_old_xmit_skbs() even for xdp send queue. >>> This is bogus since the queue has xdp_frames, not sk_buffs, thus mangled >>> device tx bytes counters because skb->len is meaningless value, and even >>> triggered oops due to general protection fault on freeing them. >>> >>> Since xdp send queues do not aquire locks, old xdp_frames should be >>> freed only in virtnet_xdp_xmit(), so just skip free_old_xmit_skbs() for >>> xdp send queues. >>> >>> Similarly virtnet_poll_tx() called free_old_xmit_skbs(). This NAPI >>> handler is called even without calling start_xmit() because cb for tx is >>> by default enabled. Once the handler is called, it enabled the cb again, >>> and then the handler would be called again. We don't need this handler >>> for XDP, so don't enable cb as well as not calling free_old_xmit_skbs(). >>> >>> Also, we need to disable tx NAPI when disabling XDP, so >>> virtnet_poll_tx() can safely access curr_queue_pairs and >>> xdp_queue_pairs, which are not atomically updated while disabling XDP. >> >> I suggest to split this into another patch or squash this part to patch 1. > This part is for invocation of is_xdp_raw_buffer_queue() from > virtnet_poll_tx(), which is added in this patch, so I'm thinking it's > more natural to keep this hunk in this patch. I see. Acked-by: Jason Wang Thanks