From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f176.google.com (mail-pg1-f176.google.com [209.85.215.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 62AFE344039 for ; Tue, 6 Jan 2026 15:39:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.176 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767713959; cv=none; b=q/dkcwBIbKt41vGkjdruuvAOLi5FyBSvciyh+ITkC3PAiVFo7ZLb2wptsIvHYtv0PHUr//ngvpDElRt9tyk0tghL+96b/LMplBW0nHLR4qRbPiLfvt6gfWg0jbCunu6qgUMo+FLEFKH24kcQ8Yy/xhkBZ0UhvSjAuLn0JegNWh4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767713959; c=relaxed/simple; bh=D4XuZS2ZZKPSGLViie1fG90SrMO9FTV7FKRiDM5R9zI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Ryq/TjI2IqJAE3/doeMFc1dOyQCDQWwWogg00GT+27SaomdiDFXdobMJ6lqI6iT5p9KvU76tiLii2BcSLHyOsuG4h6Yju75mRGu8Q0pLQ9xIbZPJVQVI2QyP7OOO3kwlqS7fPwuskr3Q6VUsUZ8/fAmOCFn+tX++Qesc+vOerP4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=S6vpMjOZ; arc=none smtp.client-ip=209.85.215.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="S6vpMjOZ" Received: by mail-pg1-f176.google.com with SMTP id 41be03b00d2f7-c2dd0c24e5cso770654a12.3 for ; Tue, 06 Jan 2026 07:39:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1767713957; x=1768318757; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=+nev3k8GrDkYwcfroMD2vo+UrG57sb0fdXcs5RtCMf0=; b=S6vpMjOZRqWdca3LDKcQDvfDsyo1UOKeorJcDUGSQzlM5emg7xtexu2X15h7m0qSeD Ibr57JuQu1xDKDfH7LbgoDYFdnyF9gQ8EjaDJbLIH2kmKFbH9eJLqQcIRgEd6CHGMdnf A/ArzBzGE753QkfZBGAAcNlDGwkSn7epFRCza2uhfJWjjLA5mdXHy4NdA4gw8ddZpDyx hAQZ69HfR4qfZaUY1M90NyELCql/nhKUztseYnNk13lMfvdq4doLX5BUnE2yLP5C/T2k mLs1glPgGlW2r/SOMMYa0z1tuMKkd/vTRkkKyePtz7WoZtlzEhUUhlPurlV0O7VPC1Lf OHLQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767713957; x=1768318757; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=+nev3k8GrDkYwcfroMD2vo+UrG57sb0fdXcs5RtCMf0=; b=mc/k+IigDwTSxkhSbPcgfD4wmKBw/SYgM3Wfo1egbdySuMXgeI+Lz8ZBrL+yrpur+U i3fGs3+TlqzWV1DxEj/LVBv3lbql91VkK4rWwfg1T/owHj8N+45JCNqLuHXXqPTgUn8n L8AHWUJwYdP3i8B2drWmCh7Tne6QcAJsao/D6R9Je26IL7pVjU+7N3ZjL5e3Fw6AMNbP HeAlqdJyuW7ME3mRO935syLlwiyb6D2sUd99hEV7ZtYIgQA/mcIWqW1jDKG144fDSA71 nEbmOmajOUKq+JbIF/oaevHnJMEcqAnNI5PE+pZC2iNhaHZ0OwzeJiFoSsu/zlDnXVZ/ qECg== X-Forwarded-Encrypted: i=1; AJvYcCX7xSft9yyuNpsD+h1tFXz3qo4zWb/3WhteGYATQ6xPNvZMeWDxfsvY/7ye/GrOrUIGWC2nQCB7ivbSRtk=@vger.kernel.org X-Gm-Message-State: AOJu0Yx5iXdAaBRFgmOfVaDKzkX6gi9LqnfM2ghoiKjLEzpzT/Oxnrd4 i1usianYlznnzUb0amdlBF8uM9usaqzL1Poe15Pt4dHaAClqecyh4a/b X-Gm-Gg: AY/fxX5yw/njb78IqJ6n/hPUHSThSJSV2H2ox46B/R1nTwKHBYzAludmCAMYNIGuPb1 lo/al0W5w3MP0POMwE1KdsQtwpceyaxD7tbtHJoZsvHCXqmmGZA+tB02Ak+tkSkrAWSqmLt/XpO 6JbMwM6FdWbfFX9Sy2sbWvO7e3xjQUfvo3PGDU+5PzRYx2aqkT7WJ9Aa+rKcyxdAGdGOrvQnbDk wZKk9S0GyFhBBG8zJsgN680jtaYIn+AlIkgI2cUv0cI+29n1GbT6aFn8lNaZBXHQmtRlGfq092G W5t5/6eW4R3UqPqIWDa1AFfn0yFgmMnN7AP42HKKepoGeuEfeUK+t2P7MM2A/xTIf7+/lul+El9 a07o+Wv9g6GMpVAKwlLaQFfkfja56ZIn5BLuOj9CUTAJktm68ysrdYvQYlg/ub8UlawTh1biHv4 y2oD4db2M0At2Ewi5Khh8I X-Google-Smtp-Source: AGHT+IF0mZFbkjRBIubqLKVOfr698jKaejtisA/43GyJJji0AoxWu2L/C2JuZyOyvdKgIUNJcZv0HA== X-Received: by 2002:a05:6a21:6da1:b0:366:584c:62ef with SMTP id adf61e73a8af0-389823c3f46mr3343295637.65.1767713956663; Tue, 06 Jan 2026 07:39:16 -0800 (PST) Received: from [192.168.0.118] ([14.187.47.150]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c4cc95d5f10sm2712050a12.26.2026.01.06.07.39.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 06 Jan 2026 07:39:16 -0800 (PST) Message-ID: Date: Tue, 6 Jan 2026 22:39:09 +0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net v3 1/3] virtio-net: don't schedule delayed refill worker To: "Michael S. Tsirkin" Cc: netdev@vger.kernel.org, Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , 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 References: <20260106150438.7425-1-minhquangbui99@gmail.com> <20260106150438.7425-2-minhquangbui99@gmail.com> <20260106100959-mutt-send-email-mst@kernel.org> Content-Language: en-US From: Bui Quang Minh In-Reply-To: <20260106100959-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/6/26 22:29, Michael S. Tsirkin wrote: > 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? I've added Cc stable already. Thanks for you review. > >> --- >> 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