From patchwork Wed May 26 08:24:35 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 448745 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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 6C0EFC2B9F7 for ; Wed, 26 May 2021 08:24:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 471C16143E for ; Wed, 26 May 2021 08:24:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232526AbhEZI0N (ORCPT ); Wed, 26 May 2021 04:26:13 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:22032 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232342AbhEZI0M (ORCPT ); Wed, 26 May 2021 04:26:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1622017481; 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=7hXo1aGEjC6ReUwtGmib1qGT2W6hQwxMtry8MQ3+Q5s=; b=U47H+rRtJmY8DaAWHr8udjajhdh1IzezqaeIFgZt8SOxSuPmxbgKF5QahW2EgYocOyLCXn jo0QQTm69X2Nf8T3PAat0VzW6shreM2w2rjwo5hVGACBCXZXcZXzalnkBWTMLL9oKo29G6 f972H5GzY5iG1Kz7Pwn95hHOUNiAllg= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-320-XDFqhoWXNrebVYPJbEnodg-1; Wed, 26 May 2021 04:24:39 -0400 X-MC-Unique: XDFqhoWXNrebVYPJbEnodg-1 Received: by mail-wr1-f72.google.com with SMTP id f16-20020a5d50d00000b0290114238aa727so47023wrt.5 for ; Wed, 26 May 2021 01:24:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=7hXo1aGEjC6ReUwtGmib1qGT2W6hQwxMtry8MQ3+Q5s=; b=hNGKjVmBiYtlyTh0HQ/S8tadzgGWFXc2LGbj7yo7SRCkJjbNOEnaan7rdJJzolre4E Dk816jTn9Z3oH+YeabJ39UFJ/5Tc6cNPxa7sWOcihu9nWI6P45eNtVhupyvnAZemZt7E 5iyjpV/K6S2EiVF9p8eFVVvCQ3s4mbjzOprzyMyDGh5+qhtlR8Cn1nF+tjEI3Cgv1zYe rIFi0/b6AjL60npRgDbhG20rtwnVBmQxW+f/JrJvGlrOyoTxTEMnsYsk8vKCj7Z3KFRY YkZPeOSdqx2lB+ZzYBytBeOiVJAWt+bk10+nk0gPo1O8NE9VcyUCK5WLktgxKl/ip3aV rqhA== X-Gm-Message-State: AOAM532Q0uW1N+9fpK5/V26nzNOuipAzamCOtqLVO2v+LqraRblj9wCU rIi8UhZS5GB3DHin5vjI5lt8Lzmym6IzrhTwRI5WJ8uqPF8k1loUrYfG0bqoaKXHhW73240KuK/ R2KpnZxIGjr02aNaA X-Received: by 2002:a1c:3d05:: with SMTP id k5mr1578835wma.9.1622017477883; Wed, 26 May 2021 01:24:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJxU85p8gyLrf0vuWCAB2u049QkVe1v5Zh6lkfS/y/mIz9iaRTlYd6RVbAfTvvyvkld+1u+lAw== X-Received: by 2002:a1c:3d05:: with SMTP id k5mr1578819wma.9.1622017477718; Wed, 26 May 2021 01:24:37 -0700 (PDT) Received: from redhat.com ([2a10:8006:fcda:0:90d:c7e7:9e26:b297]) by smtp.gmail.com with ESMTPSA id g6sm5469484wmg.10.2021.05.26.01.24.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 May 2021 01:24:37 -0700 (PDT) Date: Wed, 26 May 2021 04:24:35 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Jakub Kicinski , Wei Wang , David Miller , netdev@vger.kernel.org, Willem de Bruijn , virtualization@lists.linux-foundation.org, Jason Wang Subject: [PATCH v3 1/4] virtio_net: move tx vq operation under tx queue lock Message-ID: <20210526082423.47837-2-mst@redhat.com> References: <20210526082423.47837-1-mst@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210526082423.47837-1-mst@redhat.com> X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org It's unsafe to operate a vq from multiple threads. Unfortunately this is exactly what we do when invoking clean tx poll from rx napi. Same happens with napi-tx even without the opportunistic cleaning from the receive interrupt: that races with processing the vq in start_xmit. As a fix move everything that deals with the vq to under tx lock. Fixes: b92f1e6751a6 ("virtio-net: transmit napi") Signed-off-by: Michael S. Tsirkin --- drivers/net/virtio_net.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index ac0c143f97b4..12512d1002ec 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1508,6 +1508,8 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget) struct virtnet_info *vi = sq->vq->vdev->priv; unsigned int index = vq2txq(sq->vq); struct netdev_queue *txq; + int opaque; + bool done; if (unlikely(is_xdp_raw_buffer_queue(vi, index))) { /* We don't need to enable cb for XDP */ @@ -1517,10 +1519,28 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget) txq = netdev_get_tx_queue(vi->dev, index); __netif_tx_lock(txq, raw_smp_processor_id()); + virtqueue_disable_cb(sq->vq); free_old_xmit_skbs(sq, true); + + opaque = virtqueue_enable_cb_prepare(sq->vq); + + done = napi_complete_done(napi, 0); + + if (!done) + virtqueue_disable_cb(sq->vq); + __netif_tx_unlock(txq); - virtqueue_napi_complete(napi, sq->vq, 0); + if (done) { + if (unlikely(virtqueue_poll(sq->vq, opaque))) { + if (napi_schedule_prep(napi)) { + __netif_tx_lock(txq, raw_smp_processor_id()); + virtqueue_disable_cb(sq->vq); + __netif_tx_unlock(txq); + __napi_schedule(napi); + } + } + } if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) netif_tx_wake_queue(txq);