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 08FBFC761A6 for ; Fri, 7 Apr 2023 02:46:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239344AbjDGCqp (ORCPT ); Thu, 6 Apr 2023 22:46:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42270 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239956AbjDGCqn (ORCPT ); Thu, 6 Apr 2023 22:46:43 -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 DF0F586B9; Thu, 6 Apr 2023 19:46:40 -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 7AF74649C7; Fri, 7 Apr 2023 02:46:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 14D3BC433EF; Fri, 7 Apr 2023 02:46:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1680835599; bh=z5raEhmwE/FPqsbIHeHBjLdFu5XYEI5PD+vRQ68Ne5o=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=MfOo5PBrJYHuTa/yG7BB0n1I3I9sUOu9Y6dWTjcbxtOZtXsNAXjpG74O5NrjaA+1/ Iih0i1zeEK1PLmsUS70CkXSeww/TGnH2MovprKGwb34L9nYc3ud+xHHFVpTsePdh9p QYd5n+cEpHyWH6/YgCSI+6AhJiYNxOa+Kjjbl7mMgBset7cwzOH4ttHzb7D7eySjh3 lKGc0KvKf+oiaT9kTGd/6qyMQUYhp+QXRYUjDYndZFwfbUioa9oJM+3/y2fKE0DAu4 gRZ6Mifp3mWco0V5QN37mVrqYwBOxhr/zlcneXraaHKKZtN+VPoo5G8MvoDDEPHcA1 nntgo5i4qxqnA== Message-ID: Date: Thu, 6 Apr 2023 20:46:38 -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: Willem de Bruijn , Breno Leitao Cc: io-uring@vger.kernel.org, netdev@vger.kernel.org, kuba@kernel.org, asml.silence@gmail.com, axboe@kernel.dk, 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> From: David Ahern In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 4/6/23 12:16 PM, Willem de Bruijn wrote: > On Thu, Apr 6, 2023 at 11:59 AM Breno Leitao wrote: >> >> On Thu, Apr 06, 2023 at 11:34:28AM -0400, Willem de Bruijn wrote: >>> On Thu, Apr 6, 2023 at 10:45 AM Breno Leitao wrote: >>>> >>>> From: Breno Leitao >>>> >>>> This patchset creates the initial plumbing for a io_uring command for >>>> sockets. >>>> >>>> For now, create two uring commands for sockets, SOCKET_URING_OP_SIOCOUTQ >>>> and SOCKET_URING_OP_SIOCINQ. They are similar to ioctl operations >>>> SIOCOUTQ and SIOCINQ. In fact, the code on the protocol side itself is >>>> heavily based on the ioctl operations. >>> >>> This duplicates all the existing ioctl logic of each protocol. >>> >>> Can this just call the existing proto_ops.ioctl internally and translate from/to >>> io_uring format as needed? >> >> This is doable, and we have two options in this case: >> >> 1) Create a ioctl core function that does not call `put_user()`, and >> call it from both the `udp_ioctl` and `udp_uring_cmd`, doing the proper >> translations. Something as: >> >> int udp_ioctl_core(struct sock *sk, int cmd, unsigned long arg) >> { >> int amount; >> switch (cmd) { >> case SIOCOUTQ: { >> amount = sk_wmem_alloc_get(sk); >> break; >> } >> case SIOCINQ: { >> amount = max_t(int, 0, first_packet_length(sk)); >> break; >> } >> default: >> return -ENOIOCTLCMD; >> } >> return amount; >> } >> >> int udp_ioctl(struct sock *sk, int cmd, unsigned long arg) >> { >> int amount = udp_ioctl_core(sk, cmd, arg); >> >> return put_user(amount, (int __user *)arg); >> } >> EXPORT_SYMBOL(udp_ioctl); >> >> >> 2) Create a function for each "case entry". This seems a bit silly for >> UDP, but it makes more sense for other protocols. The code will look >> something like: >> >> int udp_ioctl(struct sock *sk, int cmd, unsigned long arg) >> { >> switch (cmd) { >> case SIOCOUTQ: >> { >> int amount = udp_ioctl_siocoutq(); >> return put_user(amount, (int __user *)arg); >> } >> ... >> } >> >> What is the best approach? > > A, the issue is that sock->ops->ioctl directly call put_user. > > I was thinking just having sock_uring_cmd call sock->ops->ioctl, like > sock_do_ioctl. > > But that would require those callbacks to return a negative error or > positive integer, rather than calling put_user. And then move the > put_user to sock_do_ioctl. Such a change is at least as much code > change as your series. Though without the ending up with code > duplication. It also works only if all ioctls only put_user of integer > size. That's true for TCP, UDP and RAW, but not sure if true more > broadly. > > Another approach may be to pass another argument to the ioctl > callbacks, whether to call put_user or return the integer and let the > caller take care of the output to user. This could possibly be > embedded in the a high-order bit of the cmd, so that it fails on ioctl > callbacks that do not support this mode. > > Of the two approaches you suggest, I find the first preferable. The first approach sounds better to me and it would be good to avoid io_uring details in the networking code (ie., cmd->sqe->cmd_op).