From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 1413033DEC2 for ; Tue, 6 Jan 2026 15:29:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767713357; cv=none; b=fthyzXFGLlY3/iUEvVKEStRafkiWfZz2/Ao537sW6es1vWNJvEphi6p3uRGMUIun4GRvCG0Wmt2/XSTfUizdckGWsITfJwHG3eQB/GgnZMaHxG4DHa4/+6NLZqjzJY2lmnamFNL5C1VLuYLeSkBoEnZvGOLKhWOeplJbK8eXze4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767713357; c=relaxed/simple; bh=ORBUTAza06yVYLn8Gg5h7JdLV16kPZGZnkfL1uLRIPY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=DEJEAnFEQuNWxn+sQ2OSbN30atzxCfRcTi2gS0dlNHENZ/Q5wVB1i/3e5VS923whNfiUx7ockUkfGCJSlUZLKriYxwFmk/93V3vrarK6rvMIZLL0sjRCfv54ixCZLdNxMSNiia2SKDRuAoDvubQRaziWy161X3zWzzOTxD24rIE= 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=gbeYNiFR; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=MAFUT2U4; arc=none smtp.client-ip=170.10.129.124 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="gbeYNiFR"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="MAFUT2U4" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1767713355; 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=6mutPiJahqf07tX0K9jDs+Vqe+Q2f0S7Ia0chn9JrkM=; b=gbeYNiFRyTfr+CotJFHf7TS83eER/rK6O9XkCojsOCNvvYVuC31RtYla8OMQCDU+L/1rtO 6IXslssyQIWMfhyDuqvbRrswhwnpdybpxtrdqhu5/wcLIfvpx8LxhvGEWqN0cwN3GteQWx ijX5B+ijfHC6IAMqF7HXTzK61h8/a4U= Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-407-XAj1ozEFMbGxxQc6Iyspuw-1; Tue, 06 Jan 2026 10:29:13 -0500 X-MC-Unique: XAj1ozEFMbGxxQc6Iyspuw-1 X-Mimecast-MFC-AGG-ID: XAj1ozEFMbGxxQc6Iyspuw_1767713352 Received: by mail-ed1-f72.google.com with SMTP id 4fb4d7f45d1cf-64981bd02a4so1464993a12.0 for ; Tue, 06 Jan 2026 07:29:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1767713352; x=1768318152; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=6mutPiJahqf07tX0K9jDs+Vqe+Q2f0S7Ia0chn9JrkM=; b=MAFUT2U473qNubruCADogESbRV4bDOTsGCx+b3RMpuMjGhzqFjxXodssogbvEakjh9 96MibGXRWJqQplWxloQSrvQHY7QeX/A3B11rrnHbzsJdcBK+HmHIy1wsiFVVucxCfoZe LfX+xULE8KA4UnPSVsLlCyjFjWn9YJCKNprAe+i4MJUcN45FZFXVnXp5fevbFHeO5yXm 5b+e88DP52hC2xKeIGdDzLcCz/A3pmIuy6o6BSYkjRealbofwZRwtWvvLqSXze25nxQp ZsCE37wmzOU9nH0Xz8KYlgUueJ6SUkbPtG5lMn/vPJtSRbfeRC9xLm451RLF7QrvqECu ZmoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767713352; x=1768318152; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=6mutPiJahqf07tX0K9jDs+Vqe+Q2f0S7Ia0chn9JrkM=; b=s2LEQf/3TA8KJkmCbrsB7dMgdaoil6ilfi/lMmDGOc9rB9hcpcpJJHD/gYgQHZOBrj 3afe3Qbg3IhU8aWvsSWpx/ey9JYNnKNLcD9dOtqeY9SrH3pxy38n6UY/0guKMynMKwqo FmYmjiIk4RVTW54GFHCSjmL7nW8UFlqPjXvSk446FtbaPbxpH8a8mD1z81T6LS/WG5ME Dj5ilpJBOZJ14GReNgOL4IsslVfFKW5Y9WOHlSetYH997L34wGjLymx9SImNQNxr/frB objCa241pHS15uXCY6D5yy6ZVs/jccHzWCx3rrG3KJfLqICctlTpHHK7loQBNDpyCYyr CqMA== X-Forwarded-Encrypted: i=1; AJvYcCVHHXuFIQI3JfElvXqcSj9LlSwOYoSev/l82cuWGQlrT4TDMJW3FQEhPD0wC10gz1/tyTfta985aiu6w2Y=@vger.kernel.org X-Gm-Message-State: AOJu0YyBzZnLQQjP8RN9QplvrJL+Paeg5fT4ckdXIJK2ApwzuvhAIXcC cQ5NNBudKCSthTxHAfn9Lq5gx3KNeh5zAJReaTZtBcNbf2KI5p6TbZHT23zWZJ0piljsbB6ERDc aN5JGjdR/kq6RVqQq9AF1lngFug8mYtTj7q9zrisBvWUr1pR6Eb06a+zvC+gVCo6E0A== X-Gm-Gg: AY/fxX56pb7wrGX41lO+QlbaX+tWxv129U/BPZWKXPM9zLoumZ9wprLmVR/4IhUrjNJ 9y7bTMbXWDnry4Kaog/0XYIxl00WQhDEhsbbRFkiHISsTwMuVAmIbTfVuewQnb46e12+DEImCqF 8FgAW0dS9rwulliXveALLegdi4c40Bo9ZkvGg4y8jhm1nTF6LFjgs2fGAEuO1CIzQL5m2TCZC0F D+hlD3HYp3v7dV080SMA7iSIp2QgIgp8OxvokRDHKzYaJyQ0yKDDfBHXO6/nGXlJsWU8u7iO62m KR+irvsrdb0dlC08FxEMyZKkH8oMjO8Q0USAvS5e39GC4rDYhkccqhUlx48pWJa76dvrePcByYb M3PIBHCDBsyL7Gp5bVs9s9yRHVZ4jNkVtEQ== X-Received: by 2002:a17:907:97c7:b0:b80:11fd:793b with SMTP id a640c23a62f3a-b8426a6849bmr317261866b.19.1767713349831; Tue, 06 Jan 2026 07:29:09 -0800 (PST) X-Google-Smtp-Source: AGHT+IGWb6y9xsvseC+MSQM10NdjJ3BS0aRkbGgQvy+bzZrBc9IB4ICJIxfQsaMFe9coDqIqquWjJA== X-Received: by 2002:a17:907:97c7:b0:b80:11fd:793b with SMTP id a640c23a62f3a-b8426a6849bmr317258866b.19.1767713349329; Tue, 06 Jan 2026 07:29:09 -0800 (PST) Received: from redhat.com (IGLD-80-230-31-118.inter.net.il. [80.230.31.118]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b842a27c760sm261977866b.24.2026.01.06.07.29.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Jan 2026 07:29:08 -0800 (PST) Date: Tue, 6 Jan 2026 10:29:05 -0500 From: "Michael S. Tsirkin" To: Bui Quang Minh Cc: netdev@vger.kernel.org, Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH net v3 1/3] virtio-net: don't schedule delayed refill worker Message-ID: <20260106100959-mutt-send-email-mst@kernel.org> References: <20260106150438.7425-1-minhquangbui99@gmail.com> <20260106150438.7425-2-minhquangbui99@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260106150438.7425-2-minhquangbui99@gmail.com> On Tue, Jan 06, 2026 at 10:04:36PM +0700, Bui Quang Minh wrote: > When we fail to refill the receive buffers, we schedule a delayed worker > to retry later. However, this worker creates some concurrency issues. > For example, when the worker runs concurrently with virtnet_xdp_set, > both need to temporarily disable queue's NAPI before enabling again. > Without proper synchronization, a deadlock can happen when > napi_disable() is called on an already disabled NAPI. That > napi_disable() call will be stuck and so will the subsequent > napi_enable() call. > > To simplify the logic and avoid further problems, we will instead retry > refilling in the next NAPI poll. > > Fixes: 4bc12818b363 ("virtio-net: disable delayed refill when pausing rx") > Reported-by: Paolo Abeni > Closes: https://netdev-ctrl.bots.linux.dev/logs/vmksft/drv-hw-dbg/results/400961/3-xdp-py/stderr > Cc: stable@vger.kernel.org > Suggested-by: Xuan Zhuo > Signed-off-by: Bui Quang Minh Acked-by: Michael S. Tsirkin and CC stable I think. Can you do that pls? > --- > drivers/net/virtio_net.c | 48 +++++++++++++++++++++------------------- > 1 file changed, 25 insertions(+), 23 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 1bb3aeca66c6..f986abf0c236 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -3046,16 +3046,16 @@ static int virtnet_receive(struct receive_queue *rq, int budget, > else > packets = virtnet_receive_packets(vi, rq, budget, xdp_xmit, &stats); > > + u64_stats_set(&stats.packets, packets); > if (rq->vq->num_free > min((unsigned int)budget, virtqueue_get_vring_size(rq->vq)) / 2) { > - if (!try_fill_recv(vi, rq, GFP_ATOMIC)) { > - spin_lock(&vi->refill_lock); > - if (vi->refill_enabled) > - schedule_delayed_work(&vi->refill, 0); > - spin_unlock(&vi->refill_lock); > - } > + if (!try_fill_recv(vi, rq, GFP_ATOMIC)) > + /* We need to retry refilling in the next NAPI poll so > + * we must return budget to make sure the NAPI is > + * repolled. > + */ > + packets = budget; > } > > - u64_stats_set(&stats.packets, packets); > u64_stats_update_begin(&rq->stats.syncp); > for (i = 0; i < ARRAY_SIZE(virtnet_rq_stats_desc); i++) { > size_t offset = virtnet_rq_stats_desc[i].offset; > @@ -3230,9 +3230,10 @@ static int virtnet_open(struct net_device *dev) > > for (i = 0; i < vi->max_queue_pairs; i++) { > if (i < vi->curr_queue_pairs) > - /* Make sure we have some buffers: if oom use wq. */ > - if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL)) > - schedule_delayed_work(&vi->refill, 0); > + /* Pre-fill rq agressively, to make sure we are ready to > + * get packets immediately. > + */ > + try_fill_recv(vi, &vi->rq[i], GFP_KERNEL); > > err = virtnet_enable_queue_pair(vi, i); > if (err < 0) > @@ -3472,16 +3473,15 @@ static void __virtnet_rx_resume(struct virtnet_info *vi, > struct receive_queue *rq, > bool refill) > { > - bool running = netif_running(vi->dev); > - bool schedule_refill = false; > + if (netif_running(vi->dev)) { > + /* Pre-fill rq agressively, to make sure we are ready to get > + * packets immediately. > + */ > + if (refill) > + try_fill_recv(vi, rq, GFP_KERNEL); > > - if (refill && !try_fill_recv(vi, rq, GFP_KERNEL)) > - schedule_refill = true; > - if (running) > virtnet_napi_enable(rq); > - > - if (schedule_refill) > - schedule_delayed_work(&vi->refill, 0); > + } > } > > static void virtnet_rx_resume_all(struct virtnet_info *vi) > @@ -3829,11 +3829,13 @@ static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs) > } > succ: > vi->curr_queue_pairs = queue_pairs; > - /* virtnet_open() will refill when device is going to up. */ > - spin_lock_bh(&vi->refill_lock); > - if (dev->flags & IFF_UP && vi->refill_enabled) > - schedule_delayed_work(&vi->refill, 0); > - spin_unlock_bh(&vi->refill_lock); > + if (dev->flags & IFF_UP) { > + local_bh_disable(); > + for (int i = 0; i < vi->curr_queue_pairs; ++i) > + virtqueue_napi_schedule(&vi->rq[i].napi, vi->rq[i].vq); > + > + local_bh_enable(); > + } > > return 0; > } > -- > 2.43.0