From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f178.google.com (mail-qk1-f178.google.com [209.85.222.178]) (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 0490E236A63 for ; Mon, 3 Mar 2025 17:00:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741021215; cv=none; b=j7qdM1yNcwUpQEsVLHjtRKPVYy0ncwFWpwIM15VBjT/wUuAOkz0rgYM3/ok6qg9ZUNKDRBQxyUD9H00EFGgWHYa74n66IidvGE3ANEwE0t7ueohsNqRHt7LqzqdPJVlZzAPPXcj0fn6neYNyy4bzFQMUg1Ht3kXQmhLGRAZSMeY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741021215; c=relaxed/simple; bh=PuyMo56E1J04N+xRFHQpuOme3py1aZX9AvRAkMmg0TQ=; h=Date:From:To:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UwJ4JMKcBhQm5QOMQW+03x97IeXGq8vBOJqLZP+adguqsLnay3yVJ/gmCh2DKshaAzcP/WvxFftWwp/rLcg9LC1O0PtH7s8Uorouqm5s++Tbb8yC/S3qVwgspNMz5Ui2zK1EXyGyMrtpL2jFyqWugX5DUmbnULlw1p2Cqlu+blY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=fastly.com; spf=pass smtp.mailfrom=fastly.com; dkim=pass (1024-bit key) header.d=fastly.com header.i=@fastly.com header.b=CrgBQViW; arc=none smtp.client-ip=209.85.222.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=fastly.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fastly.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=fastly.com header.i=@fastly.com header.b="CrgBQViW" Received: by mail-qk1-f178.google.com with SMTP id af79cd13be357-7c07b65efeeso429818585a.2 for ; Mon, 03 Mar 2025 09:00:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fastly.com; s=google; t=1741021213; x=1741626013; darn=lists.linux.dev; h=in-reply-to:content-disposition:mime-version:references :mail-followup-to:message-id:subject:to:from:date:from:to:cc:subject :date:message-id:reply-to; bh=yL69mmP3AaHszBSiFbdb5IOP3AgAgn4Zq7i8mgBTtbc=; b=CrgBQViWVGqP2lbsKLWk8Mah0gU0L702Jx0bX3Eg3fNuwN940rngI2OpgJHR6Oln0a icxKtJ+UT7HgVD+TSW077hRnBhquDe+2XjVnswQiihGUg8VU/O5WEB0fC7kDnWl4Q4o7 AfJsIaRxc8oYGrxQJtaKNKaKGtKrK2olYYEfc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1741021213; x=1741626013; h=in-reply-to:content-disposition:mime-version:references :mail-followup-to:message-id:subject:to:from:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=yL69mmP3AaHszBSiFbdb5IOP3AgAgn4Zq7i8mgBTtbc=; b=uk9NadsTpC9JSDklBQd7cflhPpF1u0vUEurp0MR3gIZjLOW6acAc44uHKBC6Y6iCyA l4otyHQiab5EaWuINJbXF4JfUgEPDuFXxeA0Xrop8V92Pmd/ZqPjImrj0va8LcUlUuTq i+fXfKYthCFyguKTCnTeXKToYBeDk6c8CH4cNfkbillKLGkoEadEF7ZlEG7nwQ5thPfJ JJXsQ/KYJ2g2cH+b6UvkXMmmZjmktRyWYkVGbAi9yKHuNsJcEivSKQUpQlYxnhKeolzP z+cV7v/7Rekf0HzNxQMutHg8NwDpTux4AzZZUo6n2Jd5niUVn2pNEcEqezJk/6ONIkuf YIiQ== X-Forwarded-Encrypted: i=1; AJvYcCVTAyuSdly71tnWfJT1lLWJQ+RAI2gIiLWvlNqIHDRUNoZVmfdez7IzZ5G9SK2Cp/avzSmCWggswecdalGwFg==@lists.linux.dev X-Gm-Message-State: AOJu0YzWhQHcf7nJWvbL+Y9nSmv5IRxlf1HY165hLcUYrh6owFAhKAb1 t+5tAocrN7O0Hvowt/UvxM3Rde55oOnb7k2KE92sVS6FyrqG78YKnki8CBlom48= X-Gm-Gg: ASbGncuS685DX9J4B0yOZvBwYRnEm177YVgptRmcUjBS+iBJJtVvqJB1Ls1iwDZ9Ytn ft7rHkyzyqJ3JFKvKcAB+cTVzwked8GGsfIBlV4ZsFwvRGcotKJ6gFSa7H91DKYo/v2QZEWqeRH B3D+KMdlSI4GFVCOFxcyVZ6lQazFAgr9ngRO3XzRl1u31pdpa4+MIb72vLsO1kRfkFXW9RvN130 lP4sxY2pBnu4NYZgUG8NdLZuUUTV281782x5cO+2O88LBI6M+k2nWgqu6SwOp9EYYA2nFY6bRpI UsM+Gq016GCj67HFQgBcNxGTXmI4b5+pgeJAv0nyQqlQVYcfhMAtVv7uqhJRre3oQ7sJuqQrMzO SNb+Z13o= X-Google-Smtp-Source: AGHT+IHlpeyEa5ZH06VbJgoLcEMoTEGviZJYbrPAPhw4YUCksto74AOTT5BgLi6sgiQez9Vt7bG6ig== X-Received: by 2002:a05:620a:27c7:b0:7c3:bcb2:f44f with SMTP id af79cd13be357-7c3bcb3000emr677131585a.17.1741021212762; Mon, 03 Mar 2025 09:00:12 -0800 (PST) Received: from LQ3V64L9R2 (ool-44c5a22e.dyn.optonline.net. [68.197.162.46]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7c36ff0f3c0sm621367685a.56.2025.03.03.09.00.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Mar 2025 09:00:12 -0800 (PST) Date: Mon, 3 Mar 2025 12:00:10 -0500 From: Joe Damato To: Jakub Kicinski , netdev@vger.kernel.org, mkarsten@uwaterloo.ca, gerhard@engleder-embedded.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, mst@redhat.com, leiyang@redhat.com, Eugenio =?iso-8859-1?Q?P=E9rez?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Paolo Abeni , "open list:VIRTIO CORE AND NET DRIVERS" , open list Subject: Re: [PATCH net-next v5 3/4] virtio-net: Map NAPIs to queues Message-ID: Mail-Followup-To: Joe Damato , Jakub Kicinski , netdev@vger.kernel.org, mkarsten@uwaterloo.ca, gerhard@engleder-embedded.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, mst@redhat.com, leiyang@redhat.com, Eugenio =?iso-8859-1?Q?P=E9rez?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Paolo Abeni , "open list:VIRTIO CORE AND NET DRIVERS" , open list References: <20250227185017.206785-1-jdamato@fastly.com> <20250227185017.206785-4-jdamato@fastly.com> <20250228182759.74de5bec@kernel.org> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Mar 03, 2025 at 11:46:10AM -0500, Joe Damato wrote: > On Fri, Feb 28, 2025 at 06:27:59PM -0800, Jakub Kicinski wrote: > > On Thu, 27 Feb 2025 18:50:13 +0000 Joe Damato wrote: > > > @@ -2870,9 +2883,15 @@ static void refill_work(struct work_struct *work) > > > for (i = 0; i < vi->curr_queue_pairs; i++) { > > > struct receive_queue *rq = &vi->rq[i]; > > > > > > + rtnl_lock(); > > > virtnet_napi_disable(rq); > > > + rtnl_unlock(); > > > + > > > still_empty = !try_fill_recv(vi, rq, GFP_KERNEL); > > > + > > > + rtnl_lock(); > > > virtnet_napi_enable(rq); > > > + rtnl_unlock(); > > > > Looks to me like refill_work is cancelled _sync while holding rtnl_lock > > from the close path. I think this could deadlock? > > Good catch, thank you! > > It looks like this is also the case in the failure path on > virtnet_open. > > Jason: do you have any suggestions? > > It looks like in both open and close disable_delayed_refill is > called first, before the cancel_delayed_work_sync. > > Would something like this solve the problem? > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 76dcd65ec0f2..457115300f05 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -2880,6 +2880,13 @@ static void refill_work(struct work_struct *work) > bool still_empty; > int i; > > + spin_lock(&vi->refill_lock); > + if (!vi->refill_enabled) { > + spin_unlock(&vi->refill_lock); > + return; > + } > + spin_unlock(&vi->refill_lock); > + > for (i = 0; i < vi->curr_queue_pairs; i++) { > struct receive_queue *rq = &vi->rq[i]; > Err, I suppose this also doesn't work because: CPU0 CPU1 rtnl_lock (before CPU0 calls disable_delayed_refill) virtnet_close refill_work rtnl_lock() cancel_sync <= deadlock Need to give this a bit more thought.