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 2B05FC433FE for ; Mon, 21 Feb 2022 09:10:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347685AbiBUJKb (ORCPT ); Mon, 21 Feb 2022 04:10:31 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:33950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347633AbiBUJKG (ORCPT ); Mon, 21 Feb 2022 04:10:06 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D2CB1D308; Mon, 21 Feb 2022 01:02:29 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id E8974B80EB2; Mon, 21 Feb 2022 09:02:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0DFFDC340E9; Mon, 21 Feb 2022 09:02:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1645434146; bh=Zb4ckic5Z4dK9ZXht8SRcy2CHoG81Msof9yeNXjcFVc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WLFIuOavLhk9+yfPWFv7U64rf0Um3hqt3D/fEBwleymilfDoGgIUOT2Q1MGECUDQx wtx7NC4HAcFZyeGmNvNciuiqIuKehJU6jRPuZjt1D5SITqNZZoDg6LaHw6EMCfA1p7 rOZfh4vBjWSAgZ4AN/Y8IJKsI76wO/rBTU3pPJRo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Srinivas Pandruvada , Hans de Goede , Sasha Levin , Liwei Song Subject: [PATCH 5.10 021/121] platform/x86: ISST: Fix possible circular locking dependency detected Date: Mon, 21 Feb 2022 09:48:33 +0100 Message-Id: <20220221084921.878966513@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220221084921.147454846@linuxfoundation.org> References: <20220221084921.147454846@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Srinivas Pandruvada [ Upstream commit 17da2d5f93692086dd096a975225ffd5622d0bf8 ] As reported: [ 256.104522] ====================================================== [ 256.113783] WARNING: possible circular locking dependency detected [ 256.120093] 5.16.0-rc6-yocto-standard+ #99 Not tainted [ 256.125362] ------------------------------------------------------ [ 256.131673] intel-speed-sel/844 is trying to acquire lock: [ 256.137290] ffffffffc036f0d0 (punit_misc_dev_lock){+.+.}-{3:3}, at: isst_if_open+0x18/0x90 [isst_if_common] [ 256.147171] [ 256.147171] but task is already holding lock: [ 256.153135] ffffffff8ee7cb50 (misc_mtx){+.+.}-{3:3}, at: misc_open+0x2a/0x170 [ 256.160407] [ 256.160407] which lock already depends on the new lock. [ 256.160407] [ 256.168712] [ 256.168712] the existing dependency chain (in reverse order) is: [ 256.176327] [ 256.176327] -> #1 (misc_mtx){+.+.}-{3:3}: [ 256.181946] lock_acquire+0x1e6/0x330 [ 256.186265] __mutex_lock+0x9b/0x9b0 [ 256.190497] mutex_lock_nested+0x1b/0x20 [ 256.195075] misc_register+0x32/0x1a0 [ 256.199390] isst_if_cdev_register+0x65/0x180 [isst_if_common] [ 256.205878] isst_if_probe+0x144/0x16e [isst_if_mmio] ... [ 256.241976] [ 256.241976] -> #0 (punit_misc_dev_lock){+.+.}-{3:3}: [ 256.248552] validate_chain+0xbc6/0x1750 [ 256.253131] __lock_acquire+0x88c/0xc10 [ 256.257618] lock_acquire+0x1e6/0x330 [ 256.261933] __mutex_lock+0x9b/0x9b0 [ 256.266165] mutex_lock_nested+0x1b/0x20 [ 256.270739] isst_if_open+0x18/0x90 [isst_if_common] [ 256.276356] misc_open+0x100/0x170 [ 256.280409] chrdev_open+0xa5/0x1e0 ... The call sequence suggested that misc_device /dev file can be opened before misc device is yet to be registered, which is done only once. Here punit_misc_dev_lock was used as common lock, to protect the registration by multiple ISST HW drivers, one time setup, prevent duplicate registry of misc device and prevent load/unload when device is open. We can split into locks: - One which just prevent duplicate call to misc_register() and one time setup. Also never call again if the misc_register() failed or required one time setup is failed. This lock is not shared with any misc device callbacks. - The other lock protects registry, load and unload of HW drivers. Sequence in isst_if_cdev_register() - Register callbacks under punit_misc_dev_open_lock - Call isst_misc_reg() which registers misc_device on the first registry which is under punit_misc_dev_reg_lock, which is not shared with callbacks. Sequence in isst_if_cdev_unregister Just opposite of isst_if_cdev_register Reported-and-tested-by: Liwei Song Signed-off-by: Srinivas Pandruvada Link: https://lore.kernel.org/r/20220112022521.54669-1-srinivas.pandruvada@linux.intel.com Reviewed-by: Hans de Goede Signed-off-by: Hans de Goede Signed-off-by: Sasha Levin --- .../intel_speed_select_if/isst_if_common.c | 97 ++++++++++++------- 1 file changed, 63 insertions(+), 34 deletions(-) diff --git a/drivers/platform/x86/intel_speed_select_if/isst_if_common.c b/drivers/platform/x86/intel_speed_select_if/isst_if_common.c index 0c2aa22c7a12e..407afafc7e83f 100644 --- a/drivers/platform/x86/intel_speed_select_if/isst_if_common.c +++ b/drivers/platform/x86/intel_speed_select_if/isst_if_common.c @@ -532,7 +532,10 @@ static long isst_if_def_ioctl(struct file *file, unsigned int cmd, return ret; } -static DEFINE_MUTEX(punit_misc_dev_lock); +/* Lock to prevent module registration when already opened by user space */ +static DEFINE_MUTEX(punit_misc_dev_open_lock); +/* Lock to allow one share misc device for all ISST interace */ +static DEFINE_MUTEX(punit_misc_dev_reg_lock); static int misc_usage_count; static int misc_device_ret; static int misc_device_open; @@ -542,7 +545,7 @@ static int isst_if_open(struct inode *inode, struct file *file) int i, ret = 0; /* Fail open, if a module is going away */ - mutex_lock(&punit_misc_dev_lock); + mutex_lock(&punit_misc_dev_open_lock); for (i = 0; i < ISST_IF_DEV_MAX; ++i) { struct isst_if_cmd_cb *cb = &punit_callbacks[i]; @@ -564,7 +567,7 @@ static int isst_if_open(struct inode *inode, struct file *file) } else { misc_device_open++; } - mutex_unlock(&punit_misc_dev_lock); + mutex_unlock(&punit_misc_dev_open_lock); return ret; } @@ -573,7 +576,7 @@ static int isst_if_relase(struct inode *inode, struct file *f) { int i; - mutex_lock(&punit_misc_dev_lock); + mutex_lock(&punit_misc_dev_open_lock); misc_device_open--; for (i = 0; i < ISST_IF_DEV_MAX; ++i) { struct isst_if_cmd_cb *cb = &punit_callbacks[i]; @@ -581,7 +584,7 @@ static int isst_if_relase(struct inode *inode, struct file *f) if (cb->registered) module_put(cb->owner); } - mutex_unlock(&punit_misc_dev_lock); + mutex_unlock(&punit_misc_dev_open_lock); return 0; } @@ -598,6 +601,43 @@ static struct miscdevice isst_if_char_driver = { .fops = &isst_if_char_driver_ops, }; +static int isst_misc_reg(void) +{ + mutex_lock(&punit_misc_dev_reg_lock); + if (misc_device_ret) + goto unlock_exit; + + if (!misc_usage_count) { + misc_device_ret = isst_if_cpu_info_init(); + if (misc_device_ret) + goto unlock_exit; + + misc_device_ret = misc_register(&isst_if_char_driver); + if (misc_device_ret) { + isst_if_cpu_info_exit(); + goto unlock_exit; + } + } + misc_usage_count++; + +unlock_exit: + mutex_unlock(&punit_misc_dev_reg_lock); + + return misc_device_ret; +} + +static void isst_misc_unreg(void) +{ + mutex_lock(&punit_misc_dev_reg_lock); + if (misc_usage_count) + misc_usage_count--; + if (!misc_usage_count && !misc_device_ret) { + misc_deregister(&isst_if_char_driver); + isst_if_cpu_info_exit(); + } + mutex_unlock(&punit_misc_dev_reg_lock); +} + /** * isst_if_cdev_register() - Register callback for IOCTL * @device_type: The device type this callback handling. @@ -615,38 +655,31 @@ static struct miscdevice isst_if_char_driver = { */ int isst_if_cdev_register(int device_type, struct isst_if_cmd_cb *cb) { - if (misc_device_ret) - return misc_device_ret; + int ret; if (device_type >= ISST_IF_DEV_MAX) return -EINVAL; - mutex_lock(&punit_misc_dev_lock); + mutex_lock(&punit_misc_dev_open_lock); + /* Device is already open, we don't want to add new callbacks */ if (misc_device_open) { - mutex_unlock(&punit_misc_dev_lock); + mutex_unlock(&punit_misc_dev_open_lock); return -EAGAIN; } - if (!misc_usage_count) { - int ret; - - misc_device_ret = misc_register(&isst_if_char_driver); - if (misc_device_ret) - goto unlock_exit; - - ret = isst_if_cpu_info_init(); - if (ret) { - misc_deregister(&isst_if_char_driver); - misc_device_ret = ret; - goto unlock_exit; - } - } memcpy(&punit_callbacks[device_type], cb, sizeof(*cb)); punit_callbacks[device_type].registered = 1; - misc_usage_count++; -unlock_exit: - mutex_unlock(&punit_misc_dev_lock); + mutex_unlock(&punit_misc_dev_open_lock); - return misc_device_ret; + ret = isst_misc_reg(); + if (ret) { + /* + * No need of mutex as the misc device register failed + * as no one can open device yet. Hence no contention. + */ + punit_callbacks[device_type].registered = 0; + return ret; + } + return 0; } EXPORT_SYMBOL_GPL(isst_if_cdev_register); @@ -661,16 +694,12 @@ EXPORT_SYMBOL_GPL(isst_if_cdev_register); */ void isst_if_cdev_unregister(int device_type) { - mutex_lock(&punit_misc_dev_lock); - misc_usage_count--; + isst_misc_unreg(); + mutex_lock(&punit_misc_dev_open_lock); punit_callbacks[device_type].registered = 0; if (device_type == ISST_IF_DEV_MBOX) isst_delete_hash(); - if (!misc_usage_count && !misc_device_ret) { - misc_deregister(&isst_if_char_driver); - isst_if_cpu_info_exit(); - } - mutex_unlock(&punit_misc_dev_lock); + mutex_unlock(&punit_misc_dev_open_lock); } EXPORT_SYMBOL_GPL(isst_if_cdev_unregister); -- 2.34.1