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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 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 In-Reply-To: <20210526082423.47837-1-mst@redhat.com> X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: Willem de Bruijn , netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, Jakub Kicinski , Wei Wang , David Miller X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" 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); -- MST _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization