From patchwork Tue Nov 3 20:36:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 317080 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 584ABC2D0A3 for ; Tue, 3 Nov 2020 21:10:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1190521534 for ; Tue, 3 Nov 2020 21:10:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604437808; bh=/XL4hkKKgI8VIEVaGhzIKtnulfGHlhePJe1s95SEA/k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=AFOckea0lUIdG0DgM/mJ7cE3ZjfMMwtD8A8vLkeBuMUVgRL2NOFnMiYR/WG3LQP44 04J/GuyXFVlgBNeHkoiqJBrlzpnPPsL1ZJwJ08XaPRtRpOgv4+gqhblPyCECnZCDI1 qZB1Kyj62mJHQAJ9uVXChPd+pV3C6SIAjARX961Q= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731626AbgKCVKH (ORCPT ); Tue, 3 Nov 2020 16:10:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:50604 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388614AbgKCVKE (ORCPT ); Tue, 3 Nov 2020 16:10:04 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8C074206B5; Tue, 3 Nov 2020 21:10:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604437804; bh=/XL4hkKKgI8VIEVaGhzIKtnulfGHlhePJe1s95SEA/k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CxSzKQ9EdVTQpxScGcynDEpbSlZw6FBxJQEoLOry5QYfh46UzA8ZvE4+nqb1zIOsn GedHixeKuqOsFCDaic55z1RJjX3p+n4bpao0cez4EY1VVJe84/M4axTo+x8yJXaoF5 jP1FN+3G1h/yp+lSiJK15oTiwbtPmWm1hA6OIN6w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lang Dai , Sasha Levin Subject: [PATCH 4.14 039/125] uio: free uio id after uio file node is freed Date: Tue, 3 Nov 2020 21:36:56 +0100 Message-Id: <20201103203202.675297682@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201103203156.372184213@linuxfoundation.org> References: <20201103203156.372184213@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Lang Dai [ Upstream commit 8fd0e2a6df262539eaa28b0a2364cca10d1dc662 ] uio_register_device() do two things. 1) get an uio id from a global pool, e.g. the id is 2) create file nodes like /sys/class/uio/uio uio_unregister_device() do two things. 1) free the uio id and return it to the global pool 2) free the file node /sys/class/uio/uio There is a situation is that one worker is calling uio_unregister_device(), and another worker is calling uio_register_device(). If the two workers are X and Y, they go as below sequence, 1) X free the uio id 2) Y get an uio id 3) Y create file node /sys/class/uio/uio 4) X free the file note /sys/class/uio/uio Then it will failed at the 3rd step and cause the phenomenon we saw as it is creating a duplicated file node. Failure reports as follows: sysfs: cannot create duplicate filename '/class/uio/uio10' Call Trace: sysfs_do_create_link_sd.isra.2+0x9e/0xb0 sysfs_create_link+0x25/0x40 device_add+0x2c4/0x640 __uio_register_device+0x1c5/0x576 [uio] adf_uio_init_bundle_dev+0x231/0x280 [intel_qat] adf_uio_register+0x1c0/0x340 [intel_qat] adf_dev_start+0x202/0x370 [intel_qat] adf_dev_start_async+0x40/0xa0 [intel_qat] process_one_work+0x14d/0x410 worker_thread+0x4b/0x460 kthread+0x105/0x140 ? process_one_work+0x410/0x410 ? kthread_bind+0x40/0x40 ret_from_fork+0x1f/0x40 Code: 85 c0 48 89 c3 74 12 b9 00 10 00 00 48 89 c2 31 f6 4c 89 ef e8 ec c4 ff ff 4c 89 e2 48 89 de 48 c7 c7 e8 b4 ee b4 e8 6a d4 d7 ff <0f> 0b 48 89 df e8 20 fa f3 ff 5b 41 5c 41 5d 5d c3 66 0f 1f 84 ---[ end trace a7531c1ed5269e84 ]--- c6xxvf b002:00:00.0: Failed to register UIO devices c6xxvf b002:00:00.0: Failed to register UIO devices Signed-off-by: Lang Dai Link: https://lore.kernel.org/r/1600054002-17722-1-git-send-email-lang.dai@intel.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/uio/uio.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index 7c18536a3742a..4fc94b5e15ef4 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -1009,8 +1009,6 @@ void uio_unregister_device(struct uio_info *info) idev = info->uio_dev; - uio_free_minor(idev); - mutex_lock(&idev->info_lock); uio_dev_del_attributes(idev); @@ -1022,6 +1020,8 @@ void uio_unregister_device(struct uio_info *info) device_unregister(&idev->dev); + uio_free_minor(idev); + return; } EXPORT_SYMBOL_GPL(uio_unregister_device);