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=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,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 A8FD2C433EF for ; Wed, 8 Sep 2021 11:19:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E87261078 for ; Wed, 8 Sep 2021 11:19:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234713AbhIHLUN (ORCPT ); Wed, 8 Sep 2021 07:20:13 -0400 Received: from out4436.biz.mail.alibaba.com ([47.88.44.36]:28481 "EHLO out4436.biz.mail.alibaba.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349071AbhIHLUE (ORCPT ); Wed, 8 Sep 2021 07:20:04 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=alimailimapcm10staff010182156082;MF=haoxu@linux.alibaba.com;NM=1;PH=DS;RN=3;SR=0;TI=SMTPD_---0UnhKikw_1631099920; Received: from B-25KNML85-0107.local(mailfrom:haoxu@linux.alibaba.com fp:SMTPD_---0UnhKikw_1631099920) by smtp.aliyun-inc.com(127.0.0.1); Wed, 08 Sep 2021 19:18:41 +0800 To: Jens Axboe , Pavel Begunkov From: Hao Xu Subject: Question about async_wake Cc: io-uring@vger.kernel.org Message-ID: Date: Wed, 8 Sep 2021 19:18:40 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Hi Jens, Pavel, I have a question about _async_wake(), would there be cases like this: async_cancel/poll_remove interrupt spin_lock_irq() list del poll->wait_entry event happens but irq disabled so interrupt delays spin_unlock_irq() generate cqe async_wake() called and generate cqe If it exists, there may be multiple -ECANCELED cqes for one req, we may do something like this to avoid it: diff --git a/fs/io_uring.c b/fs/io_uring.c index 30d959416eba..7822b2f9e890 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -5023,9 +5023,12 @@ static int __io_async_wake(struct io_kiocb *req, struct io_poll_iocb *poll, if (mask && !(mask & poll->events)) return 0; - trace_io_uring_task_add(req->ctx, req->opcode, req->user_data, mask); + if (list_empty(&poll->wait.entry)) + return 0; + else + list_del_init(&poll->wait.entry); - list_del_init(&poll->wait.entry); + trace_io_uring_task_add(req->ctx, req->opcode, req->user_data, mask); req->result = mask; req->io_task_work.func = func;