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=-16.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 4DD8BC433F5 for ; Mon, 6 Sep 2021 19:05:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 383B96054F for ; Mon, 6 Sep 2021 19:05:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243572AbhIFTGR (ORCPT ); Mon, 6 Sep 2021 15:06:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343760AbhIFTFv (ORCPT ); Mon, 6 Sep 2021 15:05:51 -0400 Received: from mail-wr1-x42c.google.com (mail-wr1-x42c.google.com [IPv6:2a00:1450:4864:20::42c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6AF31C0613C1 for ; Mon, 6 Sep 2021 12:04:46 -0700 (PDT) Received: by mail-wr1-x42c.google.com with SMTP id n5so11077100wro.12 for ; Mon, 06 Sep 2021 12:04:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=rLDEnaopW8Wpvvvt30r6PMjkqudAeyqWBRWIFXJ9nx4=; b=OQu2qB+h+DZkfGHcTWb4V7t6Twxp4Bi/SUSCLiN1N8phPsuQaH1DZJg1KgDxGaxtDX lzo0KUzCT5d2IWwyA0BcL/ZW4rQHdF2VitNbcHh1xTNyenu1e9P6Fcn9dC4DGsG06U6N Q2YGBf4o2rJKYqKMfnT2MXVBp9d9GtJIom8EFTGx14g/3Ogwh3ZuEpT/YS69RpsBuVC/ 489t6EWU8xgSsoeCqgFEdP21MWkS08GPYk2uhH5Tl3XGKsFQ2WZ463dsiCUhDdqNcRRe sIqGqWZ6t0+2gQg+nS6CoGCnZNfdbEItqQVEwfnZq8QYJN8P8YzT7p3TphS6D8grUzKf hX2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=rLDEnaopW8Wpvvvt30r6PMjkqudAeyqWBRWIFXJ9nx4=; b=Eu7WUVFq9cmlMN8SmYo7GEoTY+cz9RcXBkEZYnQyV5ySB9vbYzscF3iWWYn/NErwX0 5pEPmeMR43UgYUn+IaKhNPmvZJDnzCmBzKwTqO23k2yPDU2HhCTngj8knGCU5OKK9d23 olVZsiA9afe4bQkcV1k3MHL4Y3nXyF4IOKkvfjmeNz1aAIfGu+Vqhe/q4BxGZ3AAF5kb 9g+D2laZGo83O/PzfoXGPyvVSMXRHQVpPoor5zwGAKO8dMpy91LgRPV9DDZAe4dmaL2x q1zmACdezIEA+JZW8rzi6TJeq+uwhgqcJX7t19FcNpOHPMOkguODYdqYjLP55ioX+3Ni 3QgA== X-Gm-Message-State: AOAM533I2XVNhR3pkBk8PFdrdP+FGgUm+5ubZcvlE7HeF54jtbLfEprr R+8RDoeTLbIcWjLaEpZjb3s= X-Google-Smtp-Source: ABdhPJxJZKufDc6YmfTtWChjeta5bF5BQIsf9css1ngI8AkQJFrZSP/6wLsZnHeItIa7fSBsmpltRw== X-Received: by 2002:adf:c44b:: with SMTP id a11mr14949579wrg.416.1630955085054; Mon, 06 Sep 2021 12:04:45 -0700 (PDT) Received: from [192.168.8.197] ([148.252.133.4]) by smtp.gmail.com with ESMTPSA id z19sm415968wma.0.2021.09.06.12.04.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 06 Sep 2021 12:04:44 -0700 (PDT) Subject: Re: [PATCH 4/6] io_uring: let fast poll support multishot To: Hao Xu , Jens Axboe Cc: io-uring@vger.kernel.org, Joseph Qi References: <20210903110049.132958-1-haoxu@linux.alibaba.com> <20210903110049.132958-5-haoxu@linux.alibaba.com> From: Pavel Begunkov Message-ID: <9a8efd19-a320-29a4-7132-7b5ae5b994ff@gmail.com> Date: Mon, 6 Sep 2021 20:04:11 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210903110049.132958-5-haoxu@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 9/3/21 12:00 PM, Hao Xu wrote: > For operations like accept, multishot is a useful feature, since we can > reduce a number of accept sqe. Let's integrate it to fast poll, it may > be good for other operations in the future. > > Signed-off-by: Hao Xu > --- > fs/io_uring.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index d6df60c4cdb9..dae7044e0c24 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -5277,8 +5277,15 @@ static void io_async_task_func(struct io_kiocb *req, bool *locked) > return; > } > > - hash_del(&req->hash_node); > - io_poll_remove_double(req); > + if (READ_ONCE(apoll->poll.canceled)) > + apoll->poll.events |= EPOLLONESHOT; > + if (apoll->poll.events & EPOLLONESHOT) { > + hash_del(&req->hash_node); > + io_poll_remove_double(req); > + } else { > + add_wait_queue(apoll->poll.head, &apoll->poll.wait); It looks like it does both io_req_task_submit() and adding back to the wq, so io_issue_sqe() may be called in parallel with io_async_task_func(). If so, there will be tons of all kind of races. > + } > + > spin_unlock(&ctx->completion_lock); > > if (!READ_ONCE(apoll->poll.canceled)) > @@ -5366,7 +5373,7 @@ static int io_arm_poll_handler(struct io_kiocb *req) > struct io_ring_ctx *ctx = req->ctx; > struct async_poll *apoll; > struct io_poll_table ipt; > - __poll_t ret, mask = EPOLLONESHOT | POLLERR | POLLPRI; > + __poll_t ret, mask = POLLERR | POLLPRI; > int rw; > > if (!req->file || !file_can_poll(req->file)) > @@ -5388,6 +5395,8 @@ static int io_arm_poll_handler(struct io_kiocb *req) > rw = WRITE; > mask |= POLLOUT | POLLWRNORM; > } > + if (!(req->flags & REQ_F_APOLL_MULTISHOT)) > + mask |= EPOLLONESHOT; > > /* if we can't nonblock try, then no point in arming a poll handler */ > if (!io_file_supports_nowait(req, rw)) > -- Pavel Begunkov