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=-8.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 45D3EC43219 for ; Tue, 30 Apr 2019 13:56:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1218521734 for ; Tue, 30 Apr 2019 13:56:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="E6X+aRgl"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="JjTv4Or/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727469AbfD3N4F (ORCPT ); Tue, 30 Apr 2019 09:56:05 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:38258 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725938AbfD3N4E (ORCPT ); Tue, 30 Apr 2019 09:56:04 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 6FE0660247; Tue, 30 Apr 2019 13:56:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1556632563; bh=V74Xn+4Xecuy8X76IYwMZ5DL3OaMc8SDcfUZGzNca7Y=; h=From:To:Cc:Subject:Date:From; b=E6X+aRglJUsJVbGzBifTMnPRqeKI7HJochINZKgypPMQJwwqiTHQXXE9OGUxOMBXC SyGk2Jcrvg1vkWIa+Kw8K0aU8TKoAhhkLpn1vTPZzec9KUjN6A/d7Frji1u6d3s0JG Lr7IyX0Z2zKSbpSEGWppEI7GCkq0D2uwmnmPBOF4= Received: from prsood-linux.qualcomm.com (blr-c-bdr-fw-01_globalnat_allzones-outside.qualcomm.com [103.229.19.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: prsood@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 0D44360247; Tue, 30 Apr 2019 13:56:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1556632562; bh=V74Xn+4Xecuy8X76IYwMZ5DL3OaMc8SDcfUZGzNca7Y=; h=From:To:Cc:Subject:Date:From; b=JjTv4Or/8PdZiHbNn1HIJXS4YfXdaOZwWvx4MakDXa09Ye6adoak74p6FPzrzUMgO Zqyb62K0guI1yigEVqRzcjNXRJ2Fwjo8X9Rwt2dalh8LBoGHSCfD294htWSx3/y6YK Y0UZzE5bX6rxmNCjvBcypEwv0lzvByKaau/Eqjtg= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 0D44360247 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=prsood@codeaurora.org From: Prateek Sood To: gregkh@linuxfoundation.org, rafael@kernel.org Cc: sramana@codeaurora.org, prsood@codeaurora.org, linux-kernel@vger.kernel.org Subject: [PATCH] drivers: core: Remove glue dirs early only when refcount is 1 Date: Tue, 30 Apr 2019 19:25:40 +0530 Message-Id: <1556632540-17382-1-git-send-email-prsood@codeaurora.org> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While loading firmware blobs parallely in different threads, it is possible to free sysfs node of glue_dirs in device_del() from a thread while another thread is trying to add subdir from device_add() in glue_dirs sysfs node. CPU1 CPU2 _request_firmware_load() device_add() get_device_parent() class_dir_create_and_add() kobject_add_internal() create_dir() // glue_dir _request_firmware_load() device_add() get_device_parent() kobject_get() //glue_dir device_del() cleanup_glue_dir() kobject_del() kobject_add() kobject_add_internal() create_dir() // in glue_dir kernfs_create_dir_ns() sysfs_remove_dir() //glue_dir->sd=NULL sysfs_put() // free glue_dir->sd kernfs_new_node() kernfs_get(glue_dir) Fix this race by making sure that kernfs_node for glue_dir is released only when refcount for glue_dir kobj is 1. Signed-off-by: Prateek Sood --- drivers/base/core.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 4aeaa0c..3955d07 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1820,12 +1820,15 @@ static inline struct kobject *get_glue_dir(struct device *dev) */ static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir) { + unsigned int refcount; + /* see if we live in a "glue" directory */ if (!live_in_glue_dir(glue_dir, dev)) return; mutex_lock(&gdp_mutex); - if (!kobject_has_children(glue_dir)) + refcount = kref_read(&glue_dir->kref); + if (!kobject_has_children(glue_dir) && !--refcount) kobject_del(glue_dir); kobject_put(glue_dir); mutex_unlock(&gdp_mutex); -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.