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 374BBC43334 for ; Thu, 30 Jun 2022 09:18:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234215AbiF3JSv (ORCPT ); Thu, 30 Jun 2022 05:18:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45076 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234177AbiF3JSX (ORCPT ); Thu, 30 Jun 2022 05:18:23 -0400 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24A2C403DA for ; Thu, 30 Jun 2022 02:17:14 -0700 (PDT) Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 25U0LaG3008171 for ; Thu, 30 Jun 2022 02:17:13 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=tIhkPlWStBNk/+zkPkhwWVN8boBfp55d1HvcMzDGNpY=; b=oGcIHbH14Z8i/zpn5UX4exEbhjltNgXvXuU01I/lTGfMgsQexf3OeLgRBm5HfJtAFNwU K8rDzK7zTqd+KwJgwhKdt9MTPauQ7xVUJPYSA+Nn3z9kSsQkWpwfzDCZ0yXedELrKaED dNt69QTY2iHQ74Ly8P8oCw1bT1lmPe0NMao= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3h0qgqxdw0-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 30 Jun 2022 02:17:13 -0700 Received: from snc-exhub201.TheFacebook.com (2620:10d:c085:21d::7) by snc-exhub202.TheFacebook.com (2620:10d:c085:21d::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Thu, 30 Jun 2022 02:17:12 -0700 Received: from twshared17349.03.ash7.facebook.com (2620:10d:c085:108::8) by mail.thefacebook.com (2620:10d:c085:21d::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Thu, 30 Jun 2022 02:17:11 -0700 Received: by devbig038.lla2.facebook.com (Postfix, from userid 572232) id C05E82599FDD; Thu, 30 Jun 2022 02:14:08 -0700 (PDT) From: Dylan Yudaken To: Jens Axboe , Pavel Begunkov , CC: , , Dylan Yudaken Subject: [PATCH v2 for-next 08/12] io_uring: fix multishot poll on overflow Date: Thu, 30 Jun 2022 02:12:27 -0700 Message-ID: <20220630091231.1456789-9-dylany@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220630091231.1456789-1-dylany@fb.com> References: <20220630091231.1456789-1-dylany@fb.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-GUID: HNX4KIdWeJY9m306OJDwAkQug8A2cnvD X-Proofpoint-ORIG-GUID: HNX4KIdWeJY9m306OJDwAkQug8A2cnvD X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-06-30_05,2022-06-28_01,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On overflow, multishot poll can still complete with the IORING_CQE_F_MORE flag set. If in the meantime the user clears a CQE and a the poll was cancelled the= n the poll will post a CQE without the IORING_CQE_F_MORE (and likely result -ECANCELED). However when processing the application will encounter the non-overflow CQE which indicates that there will be no more events posted. Typical userspace applications would free memory associated with the poll in this case. It will then subsequently receive the earlier CQE which has overflowed, which breaks the contract given by the IORING_CQE_F_MORE flag. Signed-off-by: Dylan Yudaken --- io_uring/poll.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/io_uring/poll.c b/io_uring/poll.c index e8f922a4f6d7..57747d92bba4 100644 --- a/io_uring/poll.c +++ b/io_uring/poll.c @@ -243,8 +243,10 @@ static int io_poll_check_events(struct io_kiocb *req= , bool *locked) req->apoll_events); =20 if (!io_post_aux_cqe(ctx, req->cqe.user_data, - mask, IORING_CQE_F_MORE, true)) - return -ECANCELED; + mask, IORING_CQE_F_MORE, false)) { + io_req_set_res(req, mask, 0); + return IOU_POLL_REMOVE_POLL_USE_RES; + } } else { ret =3D io_poll_issue(req, locked); if (ret =3D=3D IOU_STOP_MULTISHOT) --=20 2.30.2