From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 48B7429344E for ; Mon, 14 Apr 2025 11:46:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744631189; cv=none; b=sG9RO0UJSvyS9RXGXL/r0ZB91xM/vVIs1jvdWWa+MbySnFVDmmQHZEDiyaf1SzYS9m0MOcSNVdj3zsQV+e03Ihrqh3ul32byRF6fZPFwGGhjOLip8UAyoJSslYlYTCe71+nBoBmjo6LYRStGkHCMBfSP2A0evX17oWvSHk4X9mI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744631189; c=relaxed/simple; bh=TGa5A74hhJRFatKtiDaBCJm3bNAxG+RmuZi9KC/N3rk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: In-Reply-To:Content-Type:Content-Disposition; b=mIUUs9iXjLrD1i9LFovSnFVi27GWxkbdwNmb3W+HwvdHPyddyHb5NYU+WUaNjP7zX2kVXDsOIA+Uj5PT+DavNcYUxOzU1a4LSRUfGnG79zaxgm0NhvAwu+M57AQNNWivRvQjP7jk6F4gH0klyrcCa09ihZIiwBWP1flSJwReThI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=F+rgE55F; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="F+rgE55F" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744631186; 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=zjO+mv63DF8OWXZ5ZxlPzpl6bC2oyYwvBcdRfK7EHgs=; b=F+rgE55FtJUz/FEomUw6Nknpo0zNOemVnrUR/1RI97eX71CuTPUUUwy/wxWh4WT1j5XeGg CSsSywtLxdSPgvpoZwNtWnmwE+wtJwF3/pJOzNQPR5sg2L2H9sTnCyBa0zr+j4Q90Wm0Eb JsU9gfNdn+CxcQ41IFxp2fcFOwTOw+M= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-244-6AN6xCuOPoaHb2Abqee2aA-1; Mon, 14 Apr 2025 07:46:22 -0400 X-MC-Unique: 6AN6xCuOPoaHb2Abqee2aA-1 X-Mimecast-MFC-AGG-ID: 6AN6xCuOPoaHb2Abqee2aA_1744631182 Received: by mail-wm1-f72.google.com with SMTP id 5b1f17b1804b1-43cfda30a3cso23492785e9.3 for ; Mon, 14 Apr 2025 04:46:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1744631182; x=1745235982; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=zjO+mv63DF8OWXZ5ZxlPzpl6bC2oyYwvBcdRfK7EHgs=; b=az/+oFUL6NmSdNYMqBcUYrp/cd+TUc4dzD3fcnrMZRcz/Q8ua+3XKZ9R6SkavL8miQ O4wmJUh7tKymJn11O5bpZp4F2qSADyFYGIYZHXPkErGLsBuO/uhGpdsxw4AfjVTnWejU p5RhWwCrFxpj4Qf81PQZtvEaL9YKOdlV2MDk1Q+afdhGg5369itO+4+0edlvxupUNDk+ 7skLcD8Ow9px3ybFAJq3dPM13o3rtVq/rwl2Eti3QJLaqy4P+ATBgoPnJbzRtMdEQ28m aHCuvIho9qiJs4riBxFMKBV9WWTCiS5bAc2Faf8R0Y5WnfjUieqNo6MLiUICNJCYB2pa FxXQ== X-Gm-Message-State: AOJu0Yyv/aCCzv7HTpY/w0MDq94jRwXvDCbpwT4N/hRVRSYBxxEmiume egpsK8eyaKvklueXrFmqYmzjT0upRZSzUfuJqjPi9EpWXicFfxlOp+I7IYO8Faf+wMBpyFDrTjp LP6TamWzOQbAgbtgVfuxJMPHyA52+s0GsXVRfNuQog06qy5eSoJMmo1zvWyZGq1ZY X-Gm-Gg: ASbGncvVGYOfStsdAqXdoxEkIh/Mu/9bh99M1MrQzZId2hu4Ty8c1FXMzFAq0LnldEv x6xeB5kr81GBqR4+zFLv0matuoMu4q5mvY5IOh4nCkjqFcwePG/CXUDCPqyaf/o502X1N4cd9e+ /4RXbnc4qHEc0ZSD9xqf2dzSaOhAPnsisNSUA5eRY4pR/7zD1oh/Ne2mVCoFzMNOXM3yYIMWmV2 KZ0om9rIfxX+IwXd8/t3TJlb9GP4yOidmFRrfwn/o/NfXbWaGZm+6prpv+R7zIk66vrY0LO2GDi AvnW9A== X-Received: by 2002:a05:600c:810b:b0:43c:f61e:6ea8 with SMTP id 5b1f17b1804b1-43f3a926c29mr101650525e9.2.1744631181503; Mon, 14 Apr 2025 04:46:21 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFq+5ke4eamrk9xDN2am47+k03CAk53gsv1lkSszP4cGrTySTbHEceig7E6SA/uputECe8AcA== X-Received: by 2002:a05:600c:810b:b0:43c:f61e:6ea8 with SMTP id 5b1f17b1804b1-43f3a926c29mr101650165e9.2.1744631181039; Mon, 14 Apr 2025 04:46:21 -0700 (PDT) Received: from redhat.com ([2a0d:6fc0:1517:1000:ea83:8e5f:3302:3575]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39eae96c074sm10536365f8f.28.2025.04.14.04.46.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Apr 2025 04:46:20 -0700 (PDT) Date: Mon, 14 Apr 2025 07:46:17 -0400 From: "Michael S. Tsirkin" To: Bui Quang Minh Cc: virtualization@lists.linux.dev, Jason Wang , Xuan Zhuo , Andrew Lunn , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Eugenio =?iso-8859-1?Q?P=E9rez?= , "David S . Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH v2 1/3] virtio-net: disable delayed refill when pausing rx Message-ID: <20250414074407-mutt-send-email-mst@kernel.org> References: <20250414050837.31213-1-minhquangbui99@gmail.com> <20250414050837.31213-2-minhquangbui99@gmail.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20250414050837.31213-2-minhquangbui99@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: z6rRVlFsMI1cuGn6P9wFfc_77_rAvJRR-R9B6tD9cHA_1744631182 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Apr 14, 2025 at 12:08:35PM +0700, Bui Quang Minh wrote: > When pausing rx (e.g. set up xdp, xsk pool, rx resize), we call > napi_disable() on the receive queue's napi. In delayed refill_work, it > also calls napi_disable() on the receive queue's napi. When > napi_disable() is called on an already disabled napi, it will sleep in > napi_disable_locked while still holding the netdev_lock. As a result, > later napi_enable gets stuck too as it cannot acquire the netdev_lock. > This leads to refill_work and the pause-then-resume tx are stuck > altogether. > > This scenario can be reproducible by binding a XDP socket to virtio-net > interface without setting up the fill ring. As a result, try_fill_recv > will fail until the fill ring is set up and refill_work is scheduled. > > This commit adds virtnet_rx_(pause/resume)_all helpers and fixes up the > virtnet_rx_resume to disable future and cancel all inflights delayed > refill_work before calling napi_disable() to pause the rx. > > Fixes: 413f0271f396 ("net: protect NAPI enablement with netdev_lock()") > Signed-off-by: Bui Quang Minh > --- > drivers/net/virtio_net.c | 60 ++++++++++++++++++++++++++++++++++------ > 1 file changed, 51 insertions(+), 9 deletions(-) Thans for the patch! Yes something to improve: > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 7e4617216a4b..4361b91ccc64 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -3342,10 +3342,53 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > return NETDEV_TX_OK; > } > > +static void virtnet_rx_pause_all(struct virtnet_info *vi) > +{ > + bool running = netif_running(vi->dev); > + > + /* > + * Make sure refill_work does not run concurrently to > + * avoid napi_disable race which leads to deadlock. > + */ > + disable_delayed_refill(vi); > + cancel_delayed_work_sync(&vi->refill); > + if (running) { > + int i; > + > + for (i = 0; i < vi->max_queue_pairs; i++) { > + virtnet_napi_disable(&vi->rq[i]); > + virtnet_cancel_dim(vi, &vi->rq[i].dim); duplicates a bit of code from virtnet_rx_pause_all. > + } > + } > +} > + > +static void virtnet_rx_resume_all(struct virtnet_info *vi) > +{ > + bool running = netif_running(vi->dev); > + int i; > + > + enable_delayed_refill(vi); > + for (i = 0; i < vi->max_queue_pairs; i++) { > + if (i < vi->curr_queue_pairs) { > + if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL)) > + schedule_delayed_work(&vi->refill, 0); > + } > + > + if (running) > + virtnet_napi_enable(&vi->rq[i]); > + } > +} > + > static void virtnet_rx_pause(struct virtnet_info *vi, struct receive_queue *rq) > { > bool running = netif_running(vi->dev); > > + /* > + * Make sure refill_work does not run concurrently to > + * avoid napi_disable race which leads to deadlock. > + */ > + disable_delayed_refill(vi); > + cancel_delayed_work_sync(&vi->refill); Maybe rename this e.g. __virtnet_rx_pause ? > if (running) { > virtnet_napi_disable(rq); > virtnet_cancel_dim(vi, &rq->dim); > @@ -3356,6 +3399,7 @@ static void virtnet_rx_resume(struct virtnet_info *vi, struct receive_queue *rq) > { > bool running = netif_running(vi->dev); > > + enable_delayed_refill(vi); > if (!try_fill_recv(vi, rq, GFP_KERNEL)) > schedule_delayed_work(&vi->refill, 0); > > @@ -5959,12 +6003,12 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, > if (prog) > bpf_prog_add(prog, vi->max_queue_pairs - 1); > > + virtnet_rx_pause_all(vi); > + > /* Make sure NAPI is not using any XDP TX queues for RX. */ > if (netif_running(dev)) { > - for (i = 0; i < vi->max_queue_pairs; i++) { > - virtnet_napi_disable(&vi->rq[i]); > + for (i = 0; i < vi->max_queue_pairs; i++) > virtnet_napi_tx_disable(&vi->sq[i]); > - } > } > > if (!prog) { > @@ -5996,13 +6040,12 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, > vi->xdp_enabled = false; > } > > + virtnet_rx_resume_all(vi); > for (i = 0; i < vi->max_queue_pairs; i++) { > if (old_prog) > bpf_prog_put(old_prog); > - if (netif_running(dev)) { > - virtnet_napi_enable(&vi->rq[i]); > + if (netif_running(dev)) > virtnet_napi_tx_enable(&vi->sq[i]); > - } > } > > return 0; > @@ -6014,11 +6057,10 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, > rcu_assign_pointer(vi->rq[i].xdp_prog, old_prog); > } > > + virtnet_rx_resume_all(vi); > if (netif_running(dev)) { > - for (i = 0; i < vi->max_queue_pairs; i++) { > - virtnet_napi_enable(&vi->rq[i]); > + for (i = 0; i < vi->max_queue_pairs; i++) > virtnet_napi_tx_enable(&vi->sq[i]); > - } > } > if (prog) > bpf_prog_sub(prog, vi->max_queue_pairs - 1); > -- > 2.43.0