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 666B7C77B73 for ; Tue, 11 Apr 2023 15:28:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229728AbjDKP2O (ORCPT ); Tue, 11 Apr 2023 11:28:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230215AbjDKP2M (ORCPT ); Tue, 11 Apr 2023 11:28:12 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BBE24449C; Tue, 11 Apr 2023 08:27:53 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8D11661E8B; Tue, 11 Apr 2023 15:27:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 32F66C433A0; Tue, 11 Apr 2023 15:27:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1681226863; bh=VCYh/OYFvFwLSE/is2u/m/yiwKOJLzG6IucDcL2gtuU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=RhwkO32v2hFRPjWSErmjfTwDzkchAxJlB8Jo1dTOECtA67MJTfV0kXsFO0OX21Dox Athvs6hGQHqAyc/fdABe3axnKvc+BUHrDSv/UhvU0mQ3/BJSlfO5y2cBTikv8fPJvo +ZPWqZAKQb8yzCKmprBf6JsX9X/pDnJTDgi2gtgkFfusQxwMX5+GaTdYXqwVh9aoTv n9ZDaB7lyIDhAELRD3msa+Xkl5UYc0Fp9/cH77wFS1HgK9Sz/iFQadroIERT74XnpK YAN/j9Otq7a9KHi2+OmD5pYmRWJWpkqECD2E+SueahnPkTbxYjvfHPmL/oKw101V4z rLKB/XY2/DrbQ== Message-ID: Date: Tue, 11 Apr 2023 09:27:41 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.9.1 Subject: Re: [PATCH 0/5] add initial io_uring_cmd support for sockets Content-Language: en-US To: Jens Axboe , Breno Leitao Cc: Willem de Bruijn , io-uring@vger.kernel.org, netdev@vger.kernel.org, kuba@kernel.org, asml.silence@gmail.com, leit@fb.com, edumazet@google.com, pabeni@redhat.com, davem@davemloft.net, dccp@vger.kernel.org, mptcp@lists.linux.dev, linux-kernel@vger.kernel.org, willemdebruijn.kernel@gmail.com, matthieu.baerts@tessares.net, marcelo.leitner@gmail.com References: <20230406144330.1932798-1-leitao@debian.org> <75e3c434-eb8b-66e5-5768-ca0f906979a1@kernel.org> <67831406-8d2f-feff-f56b-d0f002a95d96@kernel.dk> From: David Ahern In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 4/11/23 9:17 AM, Jens Axboe wrote: > On 4/11/23 9:10?AM, David Ahern wrote: >> On 4/11/23 8:41 AM, Jens Axboe wrote: >>> On 4/11/23 8:36?AM, David Ahern wrote: >>>> On 4/11/23 6:00 AM, Breno Leitao wrote: >>>>> I am not sure if avoiding io_uring details in network code is possible. >>>>> >>>>> The "struct proto"->uring_cmd callback implementation (tcp_uring_cmd() >>>>> in the TCP case) could be somewhere else, such as in the io_uring/ >>>>> directory, but, I think it might be cleaner if these implementations are >>>>> closer to function assignment (in the network subsystem). >>>>> >>>>> And this function (tcp_uring_cmd() for instance) is the one that I am >>>>> planning to map io_uring CMDs to ioctls. Such as SOCKET_URING_OP_SIOCINQ >>>>> -> SIOCINQ. >>>>> >>>>> Please let me know if you have any other idea in mind. >>>> >>>> I am not convinced that this io_uring_cmd is needed. This is one >>>> in-kernel subsystem calling into another, and there are APIs for that. >>>> All of this set is ioctl based and as Willem noted a little refactoring >>>> separates the get_user/put_user out so that in-kernel can call can be >>>> made with existing ops. >>> >>> How do you want to wire it up then? We can't use fops->unlocked_ioctl() >>> obviously, and we already have ->uring_cmd() for this purpose. >>> >>> I do think the right thing to do is have a common helper that returns >>> whatever value you want (or sets it), and split the ioctl parts into a >>> wrapper around that that simply copies in/out as needed. Then >>> ->uring_cmd() could call that, or you could some exported function that >>> does supports that. >>> >>> This works for the basic cases, though I do suspect we'll want to go >>> down the ->uring_cmd() at some point for more advanced cases or cases >>> that cannot sanely be done in an ioctl fashion. >>> >> >> My meta point is that there are uapis today to return this information >> to applications (and I suspect this is just the start of more networking >> changes - both data retrieval and adjusting settings). io_uring is >> wanting to do this on behalf of the application without a syscall. That >> makes io_uring yet another subsystem / component managing a socket. Any >> change to the networking stack required by io_uring should be usable by >> all other in-kernel socket owners or managers. ie., there is no reason >> for io_uring specific code here. > > I think we are in violent agreement here, what I'm describing is exactly > that - it'd make ioctl/{set,get}sockopt call into the same helpers that > ->uring_cmd() would, with the only difference being that the former > would need copy in/out and the latter would not. > > But let me just stress that for direct descriptors, we cannot currently > call ioctl or set/getsockopt. This means we have to instantiate a > regular descriptor first, do those things, then register it to never use > the regular file descriptor again. That's wasteful, and this is what we > want to enable (direct use of ioctl set/getsockopt WITHOUT a normal file > descriptor). It's not just for "oh it'd be handy to also do this from > io_uring" even if that would be a worthwhile goal in itself. > Christoph's patch set a few years back that removed set_fs broke the ability to do in-kernel ioctl and {s,g}setsockopt calls. I did not follow that change; was it a deliberate intent to not allow these in-kernel calls vs wanting to remove the set_fs? e.g., can we add a kioctl variant for in-kernel use of the APIs?