From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 3A5E762179; Thu, 1 Feb 2024 15:49:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706802593; cv=none; b=S3bviHYw9djl7w+eUzo/njOaiqlQpszHzSdE9H/gabzsqil21ZbOhdAg/cug3fU4oMxOjPFIM+PuqxCImNXQ4//Lkp5I4XQu3UHA7Zqxrs8KhmHQ7WlDCQLnNV+zo2o4SDRQQBooVCLSfZ5kErGkmqy+TKGmRmSY+AG0/9B0C68= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706802593; c=relaxed/simple; bh=yyG+tXwMfUAMz3ARIk0tUpjcZeb5q7dyZl3guKF9XEI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=KgqkK9iJ1q0u9l4EEUFePCRy4x/k9HZOspVlZV1zmykWabBWvm3Jo579rP5LQRH7oUnASR9d5TFYuFHNnjVyintuTnFPhX2srRMsCvRPPutU1lwGzUOKaNMOvrlS86SrwVVkHqgRKrB4z5j9qUHzxtGYhq65WiUGza0xn+q0rZM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=D5R878vL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D5R878vL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4578CC433F1; Thu, 1 Feb 2024 15:49:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706802593; bh=yyG+tXwMfUAMz3ARIk0tUpjcZeb5q7dyZl3guKF9XEI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=D5R878vLpp+NEpb12DzhTaXiVuha7CUkYaNGVUv4HFeSDPDHQwIZJPMu6bS+/ov/u W0I3xHDNHJ1I7+jUfB0OPmO80Km5O8eRExbsn/LLkytdUHQY0SxKimRQYvxrHiIksl 9l/KCxMV06+LvGm/VEVnI1vCOipD8duidStMHMTculmhtdoPDYgBUCN22PDZMQSvQ4 ZK38poOGk2Anq8mZ4w+g7d8xLK//MOvO7OAgpUKuHmnBkqwLuf617V1jTVNjpv3coj dXd454290CsnfBqsmdVRHewoj3XSx4nFQvHCMLvsoqIfUdqZHHzwBAa+DuZbiTYGpJ vtS2mBiIppf4w== Date: Thu, 1 Feb 2024 16:49:45 +0100 From: Simon Horman To: Souradeep Chakrabarti Cc: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, longli@microsoft.com, yury.norov@gmail.com, leon@kernel.org, cai.huoqing@linux.dev, ssengar@linux.microsoft.com, vkuznets@redhat.com, tglx@linutronix.de, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, schakrabarti@microsoft.com, stable@vger.kernel.org Subject: Re: [PATCH V2 net] hv_netvsc: Fix race condition between netvsc_probe and netvsc_remove Message-ID: <20240201154945.GH530335@kernel.org> References: <1706686551-28510-1-git-send-email-schakrabarti@linux.microsoft.com> Precedence: bulk X-Mailing-List: netdev@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: <1706686551-28510-1-git-send-email-schakrabarti@linux.microsoft.com> On Tue, Jan 30, 2024 at 11:35:51PM -0800, Souradeep Chakrabarti wrote: > In commit ac5047671758 ("hv_netvsc: Disable NAPI before closing the > VMBus channel"), napi_disable was getting called for all channels, > including all subchannels without confirming if they are enabled or not. > > This caused hv_netvsc getting hung at napi_disable, when netvsc_probe() > has finished running but nvdev->subchan_work has not started yet. > netvsc_subchan_work() -> rndis_set_subchannel() has not created the > sub-channels and because of that netvsc_sc_open() is not running. > netvsc_remove() calls cancel_work_sync(&nvdev->subchan_work), for which > netvsc_subchan_work did not run. > > netif_napi_add() sets the bit NAPI_STATE_SCHED because it ensures NAPI > cannot be scheduled. Then netvsc_sc_open() -> napi_enable will clear the > NAPIF_STATE_SCHED bit, so it can be scheduled. napi_disable() does the > opposite. > > Now during netvsc_device_remove(), when napi_disable is called for those > subchannels, napi_disable gets stuck on infinite msleep. > > This fix addresses this problem by ensuring that napi_disable() is not > getting called for non-enabled NAPI struct. > But netif_napi_del() is still necessary for these non-enabled NAPI struct > for cleanup purpose. > > Call trace: > [ 654.559417] task:modprobe state:D stack: 0 pid: 2321 ppid: 1091 flags:0x00004002 > [ 654.568030] Call Trace: > [ 654.571221] > [ 654.573790] __schedule+0x2d6/0x960 > [ 654.577733] schedule+0x69/0xf0 > [ 654.581214] schedule_timeout+0x87/0x140 > [ 654.585463] ? __bpf_trace_tick_stop+0x20/0x20 > [ 654.590291] msleep+0x2d/0x40 > [ 654.593625] napi_disable+0x2b/0x80 > [ 654.597437] netvsc_device_remove+0x8a/0x1f0 [hv_netvsc] > [ 654.603935] rndis_filter_device_remove+0x194/0x1c0 [hv_netvsc] > [ 654.611101] ? do_wait_intr+0xb0/0xb0 > [ 654.615753] netvsc_remove+0x7c/0x120 [hv_netvsc] > [ 654.621675] vmbus_remove+0x27/0x40 [hv_vmbus] > > Cc: stable@vger.kernel.org > Fixes: ac5047671758 ("hv_netvsc: Disable NAPI before closing the VMBus channel") > Signed-off-by: Souradeep Chakrabarti > Reviewed-by: Dexuan Cui > Reviewed-by: Haiyang Zhang Reviewed-by: Simon Horman