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=-12.8 required=3.0 tests=BAYES_00, 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 E06F0C43461 for ; Mon, 14 Sep 2020 03:28:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9E234208E4 for ; Mon, 14 Sep 2020 03:28:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725993AbgIND2c (ORCPT ); Sun, 13 Sep 2020 23:28:32 -0400 Received: from mga05.intel.com ([192.55.52.43]:27438 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725972AbgIND2a (ORCPT ); Sun, 13 Sep 2020 23:28:30 -0400 IronPort-SDR: BtEvS2HBjhGWgcJfsJUzn9KH/to7bA6CZRAg8RTYCDnIKRX4wtjGLqErMYGIjEBH5oZsBOLG4b 8boExQQ8xFsA== X-IronPort-AV: E=McAfee;i="6000,8403,9743"; a="243850851" X-IronPort-AV: E=Sophos;i="5.76,424,1592895600"; d="scan'208";a="243850851" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Sep 2020 20:28:29 -0700 IronPort-SDR: ht3z4prTyg6/AD7ktePHWbFV4fbVpogys0DPQki0eUnfpIYfPGCHfOEO7p5jPKTdc6/AVITSQn d2/tjp3DRjUQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,424,1592895600"; d="scan'208";a="306018259" Received: from ubuntu1604.sh.intel.com ([10.67.114.235]) by orsmga006.jf.intel.com with ESMTP; 13 Sep 2020 20:28:28 -0700 From: Lang Dai To: linux-kernel@vger.kernel.org Cc: yuan1.wang@intel.com, Lang Dai , Greg Kroah-Hartman Subject: [PATCH] uio: free uio id after uio file node is freed Date: Mon, 14 Sep 2020 11:26:41 +0800 Message-Id: <1600054002-17722-1-git-send-email-lang.dai@intel.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index 73efb80..6dca744 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -1048,8 +1048,6 @@ 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); @@ -1064,6 +1062,8 @@ void uio_unregister_device(struct uio_info *info) device_unregister(&idev->dev); + uio_free_minor(idev); + return; } EXPORT_SYMBOL_GPL(uio_unregister_device); -- 2.7.4