From patchwork Fri Dec 18 13:12:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Begunkov X-Patchwork-Id: 345945 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=-15.8 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,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 101E9C2BBCF for ; Fri, 18 Dec 2020 13:16:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BD2B423A7B for ; Fri, 18 Dec 2020 13:16:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726483AbgLRNQm (ORCPT ); Fri, 18 Dec 2020 08:16:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725885AbgLRNQm (ORCPT ); Fri, 18 Dec 2020 08:16:42 -0500 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 9103BC0617B0; Fri, 18 Dec 2020 05:16:01 -0800 (PST) Received: by mail-wr1-x42c.google.com with SMTP id r3so2123690wrt.2; Fri, 18 Dec 2020 05:16:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=dL/AuyeUrHnEUUtiBzoq8HJknDkLU9BE5SB7vIR5M88=; b=LTWbVkA83xVri9kA9HrLn3WR1O6C6WriKA6xHX9uiKof18y4TxvCqJDNDsdUaRn8c0 IP7MHYGohE4JhlyXI+Ezd5HS+iG9kVqRG1Zi6DDYJ6zRhh8IWjk9n+L//jh/hNX+G/UM 5CLIYIcRylRon05ZvAnJ64yTKD4GK3n1Hn3y2bP/OnaYb2+kjTMTTNW8C8CwVKZ4I6K5 /YgvUgBW4YxMoN7EZiJFU0KDN3JhyoawEum7b/B3sjw0yxHdMTKGNSrIBhvzaDCcC6TC eR7K8SuPrxZ3WR393aBfVKzvMPXmu4dRRx1i3vAoKNTIcxBWlS7HkjDBAwp0Gam2M2RB G2qg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=dL/AuyeUrHnEUUtiBzoq8HJknDkLU9BE5SB7vIR5M88=; b=TpvVKEyqrzzvn7eWIuOlCF6nxW8fVgpFoL6w8VHfZOoucFJwWPlUDMa1YWRIiwXtwn Gjh6DyHBZVFLLgZ7vqMOVmp/hnpO1TGhUh3yj/vvvNlVa3TJcVAIKx7Yn+G9SfenrJTp mMKF4kIujRGITq9ELgR8l0JYYpvlBZTgjoFDt9CVPH1J5Ci51emgSUsE3/HLQHobmVA2 9S3yAi8G2FYhPYk3c0ZXQP1hUNUDFWt6r7oAeVKdyA+o4Zxi8KxkNs/bJSJhL0hlCeBs OQHvngvt2PGiVTuFC6Armv56wL1ibno545esoFy+Zvr0N92SFUuGcE+pskKFJNueL3Xj oRLA== X-Gm-Message-State: AOAM530AOsnI2FyNUACBkKXy8xK4/OVDivgOrLifDWDxyEzt+FGisz14 K260JVuRypSOpvp9rtvQzys= X-Google-Smtp-Source: ABdhPJzkal/zsfw97AgYHxggEHOuyyMDqzwc7vHzT44iPN/PKW14jdvtXv+QPpwTSUp6sc5FYqwYOQ== X-Received: by 2002:adf:f6cc:: with SMTP id y12mr4427787wrp.35.1608297360336; Fri, 18 Dec 2020 05:16:00 -0800 (PST) Received: from localhost.localdomain ([85.255.234.120]) by smtp.gmail.com with ESMTPSA id b9sm12778595wmd.32.2020.12.18.05.15.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Dec 2020 05:15:59 -0800 (PST) From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org Cc: stable@vger.kernel.org Subject: [PATCH 1/8] io_uring: close a small race gap for files cancel Date: Fri, 18 Dec 2020 13:12:21 +0000 Message-Id: <68b267b21b29369fb553eb70c0c3f359c6a119c0.1608296656.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The purpose of io_uring_cancel_files() is to wait for all requests matching ->files to go/be cancelled. We should first drop files of a request in io_req_drop_files() and only then make it undiscoverable for io_uring_cancel_files. First drop, then delete from list. It's ok to leave req->id->files dangling, because it's not dereferenced by cancellation code, only compared against. It would potentially go to sleep and be awaken by following in io_req_drop_files() wake_up(). Fixes: 0f2122045b946 ("io_uring: don't rely on weak ->files references") Cc: # 5.5+ Signed-off-by: Pavel Begunkov --- fs/io_uring.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 8cf6f22afc5e..b74957856e68 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -6098,15 +6098,15 @@ static void io_req_drop_files(struct io_kiocb *req) struct io_uring_task *tctx = req->task->io_uring; unsigned long flags; + put_files_struct(req->work.identity->files); + put_nsproxy(req->work.identity->nsproxy); spin_lock_irqsave(&ctx->inflight_lock, flags); list_del(&req->inflight_entry); - if (atomic_read(&tctx->in_idle)) - wake_up(&tctx->wait); spin_unlock_irqrestore(&ctx->inflight_lock, flags); req->flags &= ~REQ_F_INFLIGHT; - put_files_struct(req->work.identity->files); - put_nsproxy(req->work.identity->nsproxy); req->work.flags &= ~IO_WQ_WORK_FILES; + if (atomic_read(&tctx->in_idle)) + wake_up(&tctx->wait); } static void __io_clean_op(struct io_kiocb *req)