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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT 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 A06F5C433C1 for ; Wed, 31 Mar 2021 09:01:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7C380619BB for ; Wed, 31 Mar 2021 09:01:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234086AbhCaJB2 (ORCPT ); Wed, 31 Mar 2021 05:01:28 -0400 Received: from out30-54.freemail.mail.aliyun.com ([115.124.30.54]:59037 "EHLO out30-54.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231156AbhCaJBO (ORCPT ); Wed, 31 Mar 2021 05:01:14 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R761e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=haoxu@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0UTx3vM-_1617181262; Received: from e18g09479.et15sqa.tbsite.net(mailfrom:haoxu@linux.alibaba.com fp:SMTPD_---0UTx3vM-_1617181262) by smtp.aliyun-inc.com(127.0.0.1); Wed, 31 Mar 2021 17:01:11 +0800 From: Hao Xu To: Jens Axboe Cc: io-uring@vger.kernel.org, Pavel Begunkov , Joseph Qi Subject: [PATCH for-5.13] io_uring: maintain drain requests' logic Date: Wed, 31 Mar 2021 17:01:02 +0800 Message-Id: <1617181262-66724-1-git-send-email-haoxu@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Now that we have multishot poll requests, one sqe can emit multiple cqes. given below example: sqe0(multishot poll)-->sqe1-->sqe2(drain req) sqe2 is designed to issue after sqe0 and sqe1 completed, but since sqe0 is a multishot poll request, sqe2 may be issued after sqe0's event triggered twice before sqe1 completed. This isn't what users leverage drain requests for. Here a simple solution is to ignore all multishot poll cqes, which means drain requests won't wait those request to be done. Signed-off-by: Hao Xu --- fs/io_uring.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 513096759445..cd6d44cf5940 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -455,6 +455,7 @@ struct io_ring_ctx { struct callback_head *exit_task_work; struct wait_queue_head hash_wait; + unsigned multishot_cqes; /* Keep this last, we don't need it for the fast path */ struct work_struct exit_work; @@ -1181,8 +1182,8 @@ static bool req_need_defer(struct io_kiocb *req, u32 seq) if (unlikely(req->flags & REQ_F_IO_DRAIN)) { struct io_ring_ctx *ctx = req->ctx; - return seq != ctx->cached_cq_tail - + READ_ONCE(ctx->cached_cq_overflow); + return seq + ctx->multishot_cqes != ctx->cached_cq_tail + + READ_ONCE(ctx->cached_cq_overflow); } return false; @@ -4897,6 +4898,7 @@ static bool io_poll_complete(struct io_kiocb *req, __poll_t mask, int error) { struct io_ring_ctx *ctx = req->ctx; unsigned flags = IORING_CQE_F_MORE; + bool multishot_poll = !(req->poll.events & EPOLLONESHOT); if (!error && req->poll.canceled) { error = -ECANCELED; @@ -4911,6 +4913,9 @@ static bool io_poll_complete(struct io_kiocb *req, __poll_t mask, int error) req->poll.done = true; flags = 0; } + if (multishot_poll) + ctx->multishot_cqes++; + io_commit_cqring(ctx); return !(flags & IORING_CQE_F_MORE); } -- 1.8.3.1