From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753517AbdJaOuy (ORCPT ); Tue, 31 Oct 2017 10:50:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44006 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751729AbdJaOux (ORCPT ); Tue, 31 Oct 2017 10:50:53 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com ED840C187208 Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=vkuznets@redhat.com From: Vitaly Kuznetsov To: David Miller Cc: eric.dumazet@gmail.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com Subject: Re: [PATCH net-next 3/4] hv_netvsc: reset net_device_ctx->nvdev with rcu_assign_pointer() References: <20171031134204.15287-4-vkuznets@redhat.com> <1509458998.3828.19.camel@edumazet-glaptop3.roam.corp.google.com> <8760avxtx5.fsf@vitty.brq.redhat.com> <20171031.234459.546020444648753386.davem@davemloft.net> Date: Tue, 31 Oct 2017 15:50:49 +0100 In-Reply-To: <20171031.234459.546020444648753386.davem@davemloft.net> (David Miller's message of "Tue, 31 Oct 2017 23:44:59 +0900 (KST)") Message-ID: <871sljxtfa.fsf@vitty.brq.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (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 [10.5.110.31]); Tue, 31 Oct 2017 14:50:53 +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: Tue, 31 Oct 2017 15:40:06 +0100 > >> Eric Dumazet writes: >> >>> On Tue, 2017-10-31 at 14:42 +0100, Vitaly Kuznetsov wrote: >>>> RCU_INIT_POINTER() is not suitable here as it doesn't give us ordering >>>> guarantees (see the comment in rcupdate.h). This is also not a hotpath. >>>> >>>> Signed-off-by: Vitaly Kuznetsov >>>> --- >>>> drivers/net/hyperv/netvsc.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c >>>> index bfc79698b8f4..12efb3e34775 100644 >>>> --- a/drivers/net/hyperv/netvsc.c >>>> +++ b/drivers/net/hyperv/netvsc.c >>>> @@ -560,7 +560,7 @@ void netvsc_device_remove(struct hv_device *device) >>>> >>>> netvsc_revoke_buf(device, net_device); >>>> >>>> - RCU_INIT_POINTER(net_device_ctx->nvdev, NULL); >>>> + rcu_assign_pointer(net_device_ctx->nvdev, NULL); >>> >>> I see no point for this patch. >>> >>> Setting a NULL pointer needs no barrier at all. >> >> Oh, sorry, I got confused by the comment near RCU_INIT_POINTER() in >> rcupdate.h. Now looking at their definitions I see. >> >> This patch can of course be dropped from the series. > > Any time there is a change to the series, you must resubmit the entire > series. > Sure, will do. Just wanted to give it a couple of days to see if Microsoft guys or someone else have any comments. Thanks, -- Vitaly