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 58E5EC77B6C for ; Thu, 13 Apr 2023 02:58:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229871AbjDMC6J (ORCPT ); Wed, 12 Apr 2023 22:58:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230098AbjDMC6G (ORCPT ); Wed, 12 Apr 2023 22:58:06 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0A951BE1 for ; Wed, 12 Apr 2023 19:57:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681354636; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=5AzEg8Ao4jgsIZn9hnvRCP42sxSvRguawETbd/Q5Ewc=; b=YTAbzPnzlrZ7EONMW+HKpSZ5XKZdEimRsN+Hrc7KMji8U+ScXMtY1AAdUIvSt4ud5qQVgX LKie4WMBUoy7T7+sqzUbfKt1ttnE4W5LBXkAFruraASj434rUMaBZU9SVhddbuz+SRUhKY uWppyGw0DQBB7U7C42cnSe8f2y/BW1Y= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-342-WKjhx5-FNSSDYZ-s21GaHw-1; Wed, 12 Apr 2023 22:57:05 -0400 X-MC-Unique: WKjhx5-FNSSDYZ-s21GaHw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8493A185A78B; Thu, 13 Apr 2023 02:57:04 +0000 (UTC) Received: from ovpn-8-18.pek2.redhat.com (ovpn-8-18.pek2.redhat.com [10.72.8.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A35AB40C83A9; Thu, 13 Apr 2023 02:56:54 +0000 (UTC) Date: Thu, 13 Apr 2023 10:56:49 +0800 From: Ming Lei To: Breno Leitao Cc: asml.silence@gmail.com, axboe@kernel.dk, davem@davemloft.net, dccp@vger.kernel.org, dsahern@kernel.org, edumazet@google.com, io-uring@vger.kernel.org, kuba@kernel.org, leit@fb.com, linux-kernel@vger.kernel.org, marcelo.leitner@gmail.com, matthieu.baerts@tessares.net, mptcp@lists.linux.dev, netdev@vger.kernel.org, pabeni@redhat.com, willemdebruijn.kernel@gmail.com, ming.lei@redhat.com Subject: Re: [PATCH RFC] io_uring: Pass whole sqe to commands Message-ID: References: <20230406144330.1932798-1-leitao@debian.org> <20230406165705.3161734-1-leitao@debian.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230406165705.3161734-1-leitao@debian.org> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Thu, Apr 06, 2023 at 09:57:05AM -0700, Breno Leitao wrote: > Currently uring CMD operation relies on having large SQEs, but future > operations might want to use normal SQE. > > The io_uring_cmd currently only saves the payload (cmd) part of the SQE, > but, for commands that use normal SQE size, it might be necessary to > access the initial SQE fields outside of the payload/cmd block. So, > saves the whole SQE other than just the pdu. > > This changes slighlty how the io_uring_cmd works, since the cmd > structures and callbacks are not opaque to io_uring anymore. I.e, the > callbacks can look at the SQE entries, not only, in the cmd structure. > > The main advantage is that we don't need to create custom structures for > simple commands. > > Suggested-by: Pavel Begunkov > Signed-off-by: Breno Leitao > --- ... > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > index 2e4c483075d3..9648134ccae1 100644 > --- a/io_uring/uring_cmd.c > +++ b/io_uring/uring_cmd.c > @@ -63,14 +63,15 @@ EXPORT_SYMBOL_GPL(io_uring_cmd_done); > int io_uring_cmd_prep_async(struct io_kiocb *req) > { > struct io_uring_cmd *ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd); > - size_t cmd_size; > + size_t size = sizeof(struct io_uring_sqe); > > BUILD_BUG_ON(uring_cmd_pdu_size(0) != 16); > BUILD_BUG_ON(uring_cmd_pdu_size(1) != 80); > > - cmd_size = uring_cmd_pdu_size(req->ctx->flags & IORING_SETUP_SQE128); > + if (req->ctx->flags & IORING_SETUP_SQE128) > + size <<= 1; > > - memcpy(req->async_data, ioucmd->cmd, cmd_size); > + memcpy(req->async_data, ioucmd->sqe, size); The copy will make some fields of sqe become READ TWICE, and driver may see different sqe field value compared with the one observed in io_init_req(). Can this kind of inconsistency cause trouble to driver? If it isn't one problem, this patch looks fine. But I guess any access on cmd->sqe in driver may have to be careful for dealing with potential post-sqe-update. Thanks, Ming