From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 304D8C7EE2F for ; Thu, 2 Mar 2023 15:09:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229690AbjCBPJU (ORCPT ); Thu, 2 Mar 2023 10:09:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42160 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229471AbjCBPJS (ORCPT ); Thu, 2 Mar 2023 10:09:18 -0500 Received: from mx.sberdevices.ru (mx.sberdevices.ru [45.89.227.171]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6632C1351A; Thu, 2 Mar 2023 07:09:15 -0800 (PST) Received: from s-lin-edge02.sberdevices.ru (localhost [127.0.0.1]) by mx.sberdevices.ru (Postfix) with ESMTP id 82B075FD0E; Thu, 2 Mar 2023 18:09:12 +0300 (MSK) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sberdevices.ru; s=mail; t=1677769752; bh=arLYnzRobVfIG4Xp6X3i9HedVCLBAhYiuD+9xD5xV54=; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; b=NuxGBxE/GMn/5Jxg6mKRWyM7waw7zJ5DmrumuRxbeMkZBAXbJ5cIXagAopnzXPPgv 6G5+EmDOjS9z2l7oIIOBVIW9ldWODX1HiqZ1npdGI9W9QrSOcqy41cBV95rpA8IY73 VoCkE1eDYGl0kt7uFKaxvoK2pLDDntzPnNc4d9PFW2FsnIBIU+oYN6bomsEe010k8k ykjduawsI13bzUlIWIiVMmu2P+gmBIbslFyObfYyhPocIAVqxrcgAD4Y86jkYIeUmM SKnP84W6gUNJUk6d+KMqM4ZKg8uW88OMyhCP3EmNgUsQjUkM7aIMektqs4hnR+Y44c x2N5bZcimqwTQ== Received: from S-MS-EXCH01.sberdevices.ru (S-MS-EXCH01.sberdevices.ru [172.16.1.4]) by mx.sberdevices.ru (Postfix) with ESMTP; Thu, 2 Mar 2023 18:09:07 +0300 (MSK) Message-ID: <63035ec9-6546-0881-353a-502b68daaada@sberdevices.ru> Date: Thu, 2 Mar 2023 18:06:19 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: [RFC PATCH v1] vsock: check error queue to set EPOLLERR Content-Language: en-US To: Stefano Garzarella CC: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , , , , , , Bobby Eshleman References: <76e7698d-890b-d14d-fa34-da5dd7dd13d8@sberdevices.ru> <20230302100621.gk45unegjbqjgpxh@sgarzare-redhat> <3b38870c-7606-bf2e-8b17-21a75a1ed751@sberdevices.ru> <20230302133845.hglm4uregjsvrcrc@sgarzare-redhat> From: Arseniy Krasnov In-Reply-To: <20230302133845.hglm4uregjsvrcrc@sgarzare-redhat> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [172.16.1.6] X-ClientProxiedBy: S-MS-EXCH01.sberdevices.ru (172.16.1.4) To S-MS-EXCH01.sberdevices.ru (172.16.1.4) X-KSMG-Rule-ID: 4 X-KSMG-Message-Action: clean X-KSMG-AntiSpam-Status: not scanned, disabled by settings X-KSMG-AntiSpam-Interceptor-Info: not scanned X-KSMG-AntiPhishing: not scanned, disabled by settings X-KSMG-AntiVirus: Kaspersky Secure Mail Gateway, version 1.1.2.30, bases: 2023/03/02 07:22:00 #20908555 X-KSMG-AntiVirus-Status: Clean, skipped Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02.03.2023 16:38, Stefano Garzarella wrote: > On Thu, Mar 02, 2023 at 02:41:29PM +0300, Arseniy Krasnov wrote: >> Hello! >> >> On 02.03.2023 13:06, Stefano Garzarella wrote: >>> On Wed, Mar 01, 2023 at 08:19:45AM +0300, Arseniy Krasnov wrote: >>>> EPOLLERR must be set not only when there is error on the socket, but also >>>> when error queue of it is not empty (may be it contains some control >>>> messages). Without this patch 'poll()' won't detect data in error queue. >>> >>> Do you have a reproducer? >>> >> Dedicated reproducer - no:) >> To reproduce this issue, i used last MSG_ZEROCOPY patches. Completion was inserted to >> error queue, and 'poll()' didn't report about it. That was the reason, why this patch >> was included to MSG_ZEROCOPY patchset. But also i think it is better to reduce number >> of patches in it(i'm working on v2), so it is good to handle this patch separately. > > Yep, absolutely! > >> May be one way to reproduce it is use SO_TIMESTAMP(time info about skbuff will be queued >> to the error queue). IIUC this feature is implemented at socket layer and may work in >> vsock (but i'm not sure). Ok, i'll check it and try to implement reproducer. >> >> IIUC, for future, policy for fixes is "for each fix implement reproducer in vsock_test"? > > Nope, but for each fix we should have a Fixes tag. > > Usually we use vsock_test to check regressions on features and also the > behaviour of different transports. > My question was more about whether this problem was there before > supporting sk_buff or not, to figure out which Fixes tag to use. > Ok i see >> >>>> This patch is based on 'tcp_poll()'. >>> >>> LGTM but we should add a Fixes tag. >>> It's not clear to me whether the problem depends on when we switched to using sk_buff or was pre-existing. >>> >>> Do you have any idea when we introduced this issue? >> git blame shows, that this code exists since first commit to vsock: > > Okay, but did we use sk_error_queue before supporting sk_buff? > No I think, sk_error_queue was unavailable to user(and still unavailable today), because we don't have check for MSG_ERRQUEUE flag in recv logic in af_vsock.c (i've added it in MSG_ZEROCOPY). So even if some subsystem of the kernel inserts skb to sk_error_queue in AF_VSOCK case, user won't dequeue it. > Anyway, if we are not sure I think we can use the following Fixes tag, > I don't see any issue if we backport this patch also before supporting > sk_buff. > Ok, i'll try to prepare reproducer(may be in vsock_test) and add Fixes tag with the commit "VSOCK: Introduce VM Sockets." Thanks, Arseniy > Thanks, > Stefano > >> >> commit d021c344051af91f42c5ba9fdedc176740cbd238 >> Author: Andy King >> Date:   Wed Feb 6 14:23:56 2013 +0000 >> >>    VSOCK: Introduce VM Sockets >> >> For TCP same logic was added by: >> >> commit 4ed2d765dfaccff5ebdac68e2064b59125033a3b >> Author: Willem de Bruijn >> Date:   Mon Aug 4 22:11:49 2014 -0400 >> >>    net-timestamp: TCP timestamping >> >> >>> >>> Thanks, >>> Stefano >>> >> >> Thanks Arseniy >> >>>> >>>> Signed-off-by: Arseniy Krasnov >>>> --- >>>> net/vmw_vsock/af_vsock.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c >>>> index 19aea7cba26e..b5e51ef4a74c 100644 >>>> --- a/net/vmw_vsock/af_vsock.c >>>> +++ b/net/vmw_vsock/af_vsock.c >>>> @@ -1026,7 +1026,7 @@ static __poll_t vsock_poll(struct file *file, struct socket *sock, >>>>     poll_wait(file, sk_sleep(sk), wait); >>>>     mask = 0; >>>> >>>> -    if (sk->sk_err) >>>> +    if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue)) >>>>         /* Signify that there has been an error on this socket. */ >>>>         mask |= EPOLLERR; >>>> >>>> --  >>>> 2.25.1 >>>> >>> >> >