From patchwork Wed Jan 31 07:35:51 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Souradeep Chakrabarti X-Patchwork-Id: 13538855 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 649645677B; Wed, 31 Jan 2024 07:36:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706686584; cv=none; b=GUF//I4gJrHcfiiqUNP52paBVXm/XCqtumN+OQ5/cxUA0zlWgqrOMwLsc3OSbcxs0OIk42/XDE3EXBSYR89DEVZYsHZF7lIBMDM9/fHfb/p2l/2tYLTxsIuDKtrAyTr4aiEOfCLy0NgowJxO6r9y6hkEFBltSSZndU0Bhobcm0M= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706686584; c=relaxed/simple; bh=5bEHW6ksJ3xqW6jJnxsmV+ldSHTTfxdpUCo76HbOvWs=; h=From:To:Cc:Subject:Date:Message-Id; b=n3DFzV8VW0Pq8oFCu4Q5VjxBWOrQoqjj804lcMjtU10e0YWd46uYkMJ5H636b+CYNtrIACRYhm9QM5EqAodnj/ZVFrVfmWd8gpqPMDxx18gRtvJV0+8aokyaWLY+Ysg9wz78kfcR7tXdC9eMPoUlopxUzXzXTDsc/ln+dj384W8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=RglxAPrU; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="RglxAPrU" Received: by linux.microsoft.com (Postfix, from userid 1099) id 4E89B2057C14; Tue, 30 Jan 2024 23:36:17 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 4E89B2057C14 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1706686577; bh=A9hod7/WJM4EPvXZpXLKwY7FnhxMOn4SZ60i2PuUqsE=; h=From:To:Cc:Subject:Date:From; b=RglxAPrUIN7r8YQ3/2n+WHKSPQEQWtIXbM7C0ahipg7d346Hb5+voReAY38R8Ijby Hwc9GhT8yNe+b6mzytI2HJwqAyibvevAQ8ng6Kqa7JS6LoL96u5AQ0t4NHP4s7raKM M6tYRnha0OFzaRpeK8wnrSf4O6n8MnDbWSson16U= From: Souradeep Chakrabarti To: 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 Cc: schakrabarti@microsoft.com, Souradeep Chakrabarti , stable@vger.kernel.org Subject: [PATCH V2 net] hv_netvsc: Fix race condition between netvsc_probe and netvsc_remove Date: Tue, 30 Jan 2024 23:35:51 -0800 Message-Id: <1706686551-28510-1-git-send-email-schakrabarti@linux.microsoft.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 --- V1 -> V2: Changed commit message, added some more details on napi NAPIF_STATE_SCHED bit set and reset. --- drivers/net/hyperv/netvsc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c index 1dafa44155d0..a6fcbda64ecc 100644 --- a/drivers/net/hyperv/netvsc.c +++ b/drivers/net/hyperv/netvsc.c @@ -708,7 +708,10 @@ void netvsc_device_remove(struct hv_device *device) /* Disable NAPI and disassociate its context from the device. */ for (i = 0; i < net_device->num_chn; i++) { /* See also vmbus_reset_channel_cb(). */ - napi_disable(&net_device->chan_table[i].napi); + /* only disable enabled NAPI channel */ + if (i < ndev->real_num_rx_queues) + napi_disable(&net_device->chan_table[i].napi); + netif_napi_del(&net_device->chan_table[i].napi); }