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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 04042C05027 for ; Mon, 30 Jan 2023 03:02:44 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pMKQh-0004kN-Jd; Sun, 29 Jan 2023 22:01:59 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pMKQf-0004hi-3h for qemu-devel@nongnu.org; Sun, 29 Jan 2023 22:01:57 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pMKQd-0006pO-8w for qemu-devel@nongnu.org; Sun, 29 Jan 2023 22:01:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675047714; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=5Ok6s27rgbvWGJO9QbfGRzIi79CMmpPjSFwPk7Wy23g=; b=LlCiVIYnR95bDVytw82LkAjxUubLDMubLZ1eykK8vZiiQt9spevTt2i3I9WtXDhz6ERkaX 4hkjTHnOPtPOFvxA4vqTayOn9jKq2/7UlYUm28n5W1dIxjYTgZXGFPGNjHtv8QnMhtuUrt Z0+fr7cPHchS/jc+SYxzd5sbgV7drHQ= Received: from mail-ot1-f72.google.com (mail-ot1-f72.google.com [209.85.210.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-270-ylJXchd2McCEZk6rwv2o4g-1; Sun, 29 Jan 2023 22:01:52 -0500 X-MC-Unique: ylJXchd2McCEZk6rwv2o4g-1 Received: by mail-ot1-f72.google.com with SMTP id y18-20020a9d6352000000b00686b3ef5990so5148804otk.11 for ; Sun, 29 Jan 2023 19:01:52 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=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=5Ok6s27rgbvWGJO9QbfGRzIi79CMmpPjSFwPk7Wy23g=; b=f5Gg1R3YZK9pNLuj+zVFbtG+ba2qDqtcT0s3QQeLMDbk58yI2SHipxRcgml+sMcFcY KTbpeZru8oKybWQZ85ubWTVan8oufubkZ4df5Od+HFRYHvbyhA3RbN7Ar+nXDoJhPMn8 7uBCy/tvoMRx5HHW37dTPslScQn8sIFz6+6XaRTFHhvWrWq0AirFIFY1ffqohARyrYD/ f7kQv9diogYLbrdKLyys1ysSRZuUIJEWnf4qbrZJjqcVr4Pg6JECzc20lyfuDKcKfkTF A65VAKK72v9VUORQsjhGOEP4IN4QptkI9ivjbEx44MKfGoxzaesEAQs7sx7UOlS9yNsk aHRw== X-Gm-Message-State: AO0yUKXJd+pEAV1XQ5vHju8M/QcljRGsrXyYiwHqfs9KdG2qsaEzDKpg 5nw/gFGAIYiG8JP21mFhcvfCl8E45kdEYnfr71hwE19aKTNEmMhnpoyFsDNCPieRr50fsLSUbY9 JAV1nZ8eYGCb2pkek3TRw742f5rIeqg0= X-Received: by 2002:a05:6870:959e:b0:163:9cea:eea7 with SMTP id k30-20020a056870959e00b001639ceaeea7mr257606oao.35.1675047712090; Sun, 29 Jan 2023 19:01:52 -0800 (PST) X-Google-Smtp-Source: AK7set90nbwtpIeaqu/hcdpsZ4BY3HtlXkbDg0juRD9m1Q2SeIxCrNlJL8P/Py8RCR8JHrMZufa5qS0X5znSA0l+0ZQ= X-Received: by 2002:a05:6870:959e:b0:163:9cea:eea7 with SMTP id k30-20020a056870959e00b001639ceaeea7mr257599oao.35.1675047711817; Sun, 29 Jan 2023 19:01:51 -0800 (PST) MIME-Version: 1.0 References: <20230129025150.119972-1-xuanzhuo@linux.alibaba.com> <20230129025150.119972-3-xuanzhuo@linux.alibaba.com> <1674978207.8889825-4-xuanzhuo@linux.alibaba.com> In-Reply-To: <1674978207.8889825-4-xuanzhuo@linux.alibaba.com> From: Jason Wang Date: Mon, 30 Jan 2023 11:01:40 +0800 Message-ID: Subject: Re: [PATCH v1 2/2] virtio-net: virtio_net_flush_tx() check for per-queue reset To: Xuan Zhuo Cc: qemu-devel@nongnu.org, "Michael S. Tsirkin" , Alexander Bulekov Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=170.10.133.124; envelope-from=jasowang@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Sun, Jan 29, 2023 at 3:44 PM Xuan Zhuo wrote: > > On Sun, 29 Jan 2023 14:23:21 +0800, Jason Wang wrote: > > On Sun, Jan 29, 2023 at 10:52 AM Xuan Zhuo wrote: > > > > > > Check whether it is per-queue reset state in virtio_net_flush_tx(). > > > > > > Before per-queue reset, we need to recover async tx resources. At this > > > time, virtio_net_flush_tx() is called, but we should not try to send > > > new packets, so virtio_net_flush_tx() should check the current > > > per-queue reset state. > > > > > > Fixes: 7dc6be52 ("virtio-net: support queue reset") > > > Fixes: https://gitlab.com/qemu-project/qemu/-/issues/1451 > > > Reported-by: Alexander Bulekov > > > Signed-off-by: Xuan Zhuo > > > --- > > > hw/net/virtio-net.c | 3 ++- > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > > > index 3ae909041a..fba6451a50 100644 > > > --- a/hw/net/virtio-net.c > > > +++ b/hw/net/virtio-net.c > > > @@ -2627,7 +2627,8 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q) > > > VirtQueueElement *elem; > > > int32_t num_packets = 0; > > > int queue_index = vq2q(virtio_get_queue_index(q->tx_vq)); > > > - if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) { > > > + if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) || > > > + virtio_queue_reset_state(q->tx_vq)) { > > > > We have other places that check DRIVER_OK do we need to check queue > > reset as well? > > I checked it again. I still think that the location of other checking DRIVER_OK > does not need to check the queue reset. For example, if we don't disable can_receive() when the queue is reset, it means rx may go for virtio_net_receive_rcu(). It means the Qemu is still trying to process the traffic from the network backend like tap which may waste cpu cycles. I think the correct way is to return false when the queue is reset in can_receive(), then the backend poll will be disabled (e.g TAP). When the queue is enabled again, qemu_flush_queued_packets() will wake up the backend polling. Having had time to check other places but it would be better to mention why it doesn't need a check in the changelog. Thanks > > Thanks. > > > > > > E.g: > > virtio_net_can_receive() > > virtio_net_tx_{timer|bh}() > > > > Thanks > > > > > return num_packets; > > > } > > > > > > -- > > > 2.32.0.3.g01195cf9f > > > > > >