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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C644C4360C for ; Fri, 11 Oct 2019 03:07:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 28B99206A1 for ; Fri, 11 Oct 2019 03:07:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726177AbfJKDHM convert rfc822-to-8bit (ORCPT ); Thu, 10 Oct 2019 23:07:12 -0400 Received: from smtpbgeu1.qq.com ([52.59.177.22]:57305 "EHLO smtpbgeu1.qq.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726076AbfJKDHM (ORCPT ); Thu, 10 Oct 2019 23:07:12 -0400 X-QQ-mid: bizesmtp26t1570763190t2zsd2mj Received: from [172.20.0.236] (unknown [218.76.23.26]) by esmtp10.qq.com (ESMTP) with id ; Fri, 11 Oct 2019 11:06:29 +0800 (CST) X-QQ-SSF: 00400000000000S0ZT90000A0000000 X-QQ-FEAT: IlL3FBEFeNhf2+Y44A7CG79jQ/f0DuQyZZDLs7NkHFeA+M3B36sd9Qi+fIGjm pGImsEz+gcz8CxIfvKnBU7dl2qXa+Qk8RBg+XeUCG5Xxia7MGYDzcM6mn7VCOQZnhrFd60H ByblAvQnWE6u3n1EzN5YKbRRDX56z0h09KwJI6p4lDIVE6zTU8eXu83jqCRuG0Jl6JwA+59 zrOUlovlLQ1vD7MjjWBd/gTUzIpRwxUEVS5B6SerOcgfur8cYFBYqlc2CpXp9KytFYGzy9i 1rHySBaXwdU95zt7S/+9Tor7Mm/Cr8MFcgUfempIfu4e1aMrsgUYln7pjOr96u5X1IAQCgS lU+tOO4Jwh7wBrm4b/IkNwp7q5A+Q== X-QQ-GoodBg: 2 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 13.0 \(3594.4.19\)) Subject: Re: [PATCH 1/2] io_uring: make the logic clearer for io_sequence_defer From: Jackie Liu In-Reply-To: <597dc8a4-b9db-f0b7-21b5-12050f07e766@kernel.dk> Date: Fri, 11 Oct 2019 11:06:28 +0800 Cc: yangerkun , linux-block@vger.kernel.org Content-Transfer-Encoding: 8BIT Message-Id: <544E51DB-7774-4DDF-A897-7A957AE2CDEB@kylinos.cn> References: <20191009011959.2203-1-liuyun01@kylinos.cn> <7af32ce6-dc8f-6683-2b99-95eefb598bff@huawei.com> <597dc8a4-b9db-f0b7-21b5-12050f07e766@kernel.dk> To: Jens Axboe X-Mailer: Apple Mail (2.3594.4.19) X-QQ-SENDSIZE: 520 Feedback-ID: bizesmtp:kylinos.cn:qybgforeign:qybgforeign4 X-QQ-Bgrelay: 1 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org > 2019年10月11日 10:35，Jens Axboe 写道： > > On 10/10/19 8:24 PM, yangerkun wrote: >> >> >> On 2019/10/9 9:19, Jackie Liu wrote: >>> __io_get_deferred_req is used to get all defer lists, including defer_list >>> and timeout_list, but io_sequence_defer should be only cares about the sequence. >>> >>> Signed-off-by: Jackie Liu >>> --- >>> fs/io_uring.c | 13 +++++-------- >>> 1 file changed, 5 insertions(+), 8 deletions(-) >>> >>> diff --git a/fs/io_uring.c b/fs/io_uring.c >>> index 8a0381f1a43b..8ec2443eb019 100644 >>> --- a/fs/io_uring.c >>> +++ b/fs/io_uring.c >>> @@ -418,9 +418,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p) >>> static inline bool io_sequence_defer(struct io_ring_ctx *ctx, >>> struct io_kiocb *req) >>> { >>> - /* timeout requests always honor sequence */ >>> - if (!(req->flags & REQ_F_TIMEOUT) && >>> - (req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN) >>> + if ((req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN) >>> return false; >>> >>> return req->sequence != ctx->cached_cq_tail + ctx->rings->sq_dropped; >>> @@ -435,12 +433,11 @@ static struct io_kiocb *__io_get_deferred_req(struct io_ring_ctx *ctx, >>> return NULL; >>> >>> req = list_first_entry(list, struct io_kiocb, list); >>> - if (!io_sequence_defer(ctx, req)) { >>> - list_del_init(&req->list); >>> - return req; >>> - } >>> + if (!(req->flags & REQ_F_TIMEOUT) && io_sequence_defer(ctx, req)) >>> + return NULL; >> Hi, >> >> For timeout req, we should also compare the sequence to determine to >> return NULL or the req. But now we will return req directly. Actually, >> no need to compare req->flags with REQ_F_TIMEOUT. > > Yes, not sure how I missed this, the patch is broken as-is. I will kill > it, cleanup can be done differently. Sorry for miss it, I don't wanna change the logic, it's not my original meaning. Personal opinion, timeout list should not be mixed with defer_list, which makes the code more complicated and difficult to understand. -- BR, Jackie Liu