From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161228AbcFIIxl (ORCPT ); Thu, 9 Jun 2016 04:53:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47076 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752067AbcFIIxi (ORCPT ); Thu, 9 Jun 2016 04:53:38 -0400 From: Vitaly Kuznetsov To: David Miller Cc: netdev@vger.kernel.org, devel@linuxdriverproject.org, linux-kernel@vger.kernel.org, kys@microsoft.com, haiyangz@microsoft.com Subject: Re: [PATCH net-next v2] netvsc: get rid of completion timeouts References: <1465406261-20233-1-git-send-email-vkuznets@redhat.com> <20160608.113220.1066436035256605334.davem@davemloft.net> Date: Thu, 09 Jun 2016 10:53:34 +0200 In-Reply-To: <20160608.113220.1066436035256605334.davem@davemloft.net> (David Miller's message of "Wed, 08 Jun 2016 11:32:20 -0700 (PDT)") Message-ID: <87eg86agkx.fsf@vitty.brq.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Thu, 09 Jun 2016 08:53:37 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Miller writes: > From: Vitaly Kuznetsov > Date: Wed, 8 Jun 2016 19:17:41 +0200 > >> I'm hitting 5 second timeout in rndis_filter_set_rss_param() while setting >> RSS parameters for the device. When this happens we end up returning >> -ETIMEDOUT from the function and rndis_filter_device_add() falls back to >> setting >> >> net_device->max_chn = 1; >> net_device->num_chn = 1; >> net_device->num_sc_offered = 0; >> >> but after a moment the rndis request succeeds and subchannels start to >> appear. netvsc_sc_open() does unconditional nvscdev->num_sc_offered-- and >> it becomes U32_MAX-1. Consequent rndis_filter_device_remove() will hang >> while waiting for all U32_MAX-1 subchannels to appear and this is not >> going to happen. >> >> The immediate issue could be solved by adding num_sc_offered > 0 check to >> netvsc_sc_open() but we're getting out of sync with the host and it's not >> easy to adjust things later, e.g. in this particular case we'll be creating >> queues without a user request for it and races are expected. Same applies >> to other parts of the driver which have the same completion timeout. >> >> Following the trend in drivers/hv/* code I suggest we remove all these >> timeouts completely. As a guest we can always trust the host we're running >> on and if the host screws things up there is no easy way to recover anyway. >> >> Signed-off-by: Vitaly Kuznetsov >> Acked-by: Haiyang Zhang > > This doesn't apply cleanly to net-next, I get rejects. Sorry for the screw up, apparently I forgot about my own cleanups I sent before. v3 is coming. -- Vitaly