From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964901AbdBQXbD (ORCPT ); Fri, 17 Feb 2017 18:31:03 -0500 Received: from mail-pg0-f65.google.com ([74.125.83.65]:35407 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964829AbdBQXbB (ORCPT ); Fri, 17 Feb 2017 18:31:01 -0500 Subject: Re: [PATCH net-next] virito-net: set queues after reset during xdp_set To: Jason Wang , mst@redhat.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <1487149689-28957-1-git-send-email-jasowang@redhat.com> <58A681E7.80907@gmail.com> From: John Fastabend Message-ID: <58A787AB.6000201@gmail.com> Date: Fri, 17 Feb 2017 15:30:51 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17-02-16 09:10 PM, Jason Wang wrote: > > > On 2017年02月17日 12:53, John Fastabend wrote: >> On 17-02-15 01:08 AM, Jason Wang wrote: >>> We set queues before reset which will cause a crash[1]. This is >>> because is_xdp_raw_buffer_queue() depends on the old xdp queue pairs >>> number to do the correct detection. So fix this by: >>> >>> - set queues after reset, to keep the old vi->curr_queue_pairs. (in >>> fact setting queues before reset does not works since after feature >>> set, all queue pairs were enabled by default during reset). >>> - change xdp_queue_pairs only after virtnet_reset() is succeed. >>> >>> [1] >> I'm guessing this occurs when enabling XDP while receiving lots of traffic? > > I hit this then disabling XDP while receiving lots of traffic. > [...] >>> + vi->xdp_queue_pairs = xdp_qp; >> But xdp_queue_pairs is being used to detect if we should allocate the XDP >> headroom. If we move it here do we have a set of buffers in the ring without >> the proper headroom when we assign the xdp program below? > > Right, so how about passing xdp_queue_pairs as a parameter to virtnet_reset(). > Then virtnet_reset() can set it after _remove_vq_common() but before > virtnet_restore_up()? > > Thanks > Sounds like a reasonable fix to me. >> >>> + } >>> + >>> + err = _virtnet_set_queues(vi, curr_qp + xdp_qp); >>> + if (err) { >>> + dev_warn(&dev->dev, "XDP Device queue allocation failure.\n"); >>> + goto virtio_queue_err; >>> } >>> netif_set_real_num_rx_queues(dev, curr_qp + xdp_qp); >>> @@ -1844,17 +1844,18 @@ static int virtnet_xdp_set(struct net_device *dev, >>> struct bpf_prog *prog) >>> return 0; >> Thanks, >> John >> >