From nobody Fri Oct 24 20:26:41 2025 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 3AEADC25B08 for ; Mon, 15 Aug 2022 22:00:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245305AbiHOWAD (ORCPT ); Mon, 15 Aug 2022 18:00:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55904 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244496AbiHOV7S (ORCPT ); Mon, 15 Aug 2022 17:59:18 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 83A6F10E949; Mon, 15 Aug 2022 12:35:05 -0700 (PDT) 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 sin.source.kernel.org (Postfix) with ESMTPS id 6EFB8CE12E0; Mon, 15 Aug 2022 19:34:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4428DC433D7; Mon, 15 Aug 2022 19:34:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660592071; bh=2wEmTjhGcMoUyc8RMh2YSMUxxlVkaz9yxKNpzM825EQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gyQKfJvsf780D38RU/nEGg67JKrC4cP3dhVedXYpW4JQ2V7Nnh1G07JAd6+mLSjOJ YLE0HkWshrDttOa6apW1cdtKj6BAswEm13PCpv7pOOzoi4lb2Rxim58twjLVRfKx8G Ky7biVM90Y1HayZqL/MTMn8zRLBQVUVv5i0AV/5I= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Suzuki Poulose , Mike Leach , Mathieu Poirier , Sasha Levin Subject: [PATCH 5.18 0697/1095] coresight: configfs: Fix unload of configurations on module exit Date: Mon, 15 Aug 2022 20:01:36 +0200 Message-Id: <20220815180458.210907254@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180429.240518113@linuxfoundation.org> References: <20220815180429.240518113@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Mike Leach [ Upstream commit 199380decc5f9188a9e65676031950f1734aaffe ] Any loaded configurations must be correctly unloaded on coresight module exit, or issues can arise with nested locking in the configfs directory code if built with CONFIG_LOCKDEP. Prior to this patch, the preloaded configuration configfs directory entries were being unloaded by the recursive code in configfs_unregister_subsystem(). However, when built with CONFIG_LOCKDEP, this caused a nested lock warning, which was not mitigated by the LOCKDEP dependent code in fs/configfs/dir.c designed to prevent this, due to the different directory levels for the root of the directory being removed. As the preloaded (and all other) configurations are registered after configfs_register_subsystem(), we now explicitly unload them before the call to configfs_unregister_subsystem(). The new routine cscfg_unload_cfgs_on_exit() iterates through the load owner list to unload any remaining configurations that were not unloaded by the user before the module exits. This covers both the CSCFG_OWNER_PRELOAD and CSCFG_OWNER_MODULE owner types, and will be extended to cover future load owner types for CoreSight configurations. Fixes: eb2ec49606c2 ("coresight: syscfg: Update load API for config loadabl= e modules") Reported-by: Suzuki Poulose Signed-off-by: Mike Leach Reviewed-and-tested-by: Suzuki K Poulose Link: https://lore.kernel.org/r/20220628173004.30002-2-mike.leach@linaro.org Signed-off-by: Mathieu Poirier Signed-off-by: Sasha Levin --- .../hwtracing/coresight/coresight-syscfg.c | 104 ++++++++++++++++-- 1 file changed, 93 insertions(+), 11 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtra= cing/coresight/coresight-syscfg.c index 11850fd8c3b5..17e728ab5c99 100644 --- a/drivers/hwtracing/coresight/coresight-syscfg.c +++ b/drivers/hwtracing/coresight/coresight-syscfg.c @@ -414,6 +414,27 @@ static void cscfg_remove_owned_csdev_features(struct c= oresight_device *csdev, vo } } =20 +/* + * Unregister all configuration and features from configfs owned by load_o= wner. + * Although this is called without the list mutex being held, it is in the + * context of an unload operation which are strictly serialised, + * so the lists cannot change during this call. + */ +static void cscfg_fs_unregister_cfgs_feats(void *load_owner) +{ + struct cscfg_config_desc *config_desc; + struct cscfg_feature_desc *feat_desc; + + list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) { + if (config_desc->load_owner =3D=3D load_owner) + cscfg_configfs_del_config(config_desc); + } + list_for_each_entry(feat_desc, &cscfg_mgr->feat_desc_list, item) { + if (feat_desc->load_owner =3D=3D load_owner) + cscfg_configfs_del_feature(feat_desc); + } +} + /* * removal is relatively easy - just remove from all lists, anything that * matches the owner. Memory for the descriptors will be managed by the ow= ner, @@ -1022,8 +1043,10 @@ struct device *cscfg_device(void) /* Must have a release function or the kernel will complain on module unlo= ad */ static void cscfg_dev_release(struct device *dev) { + mutex_lock(&cscfg_mutex); kfree(cscfg_mgr); cscfg_mgr =3D NULL; + mutex_unlock(&cscfg_mutex); } =20 /* a device is needed to "own" some kernel elements such as sysfs entries.= */ @@ -1042,6 +1065,13 @@ static int cscfg_create_device(void) if (!cscfg_mgr) goto create_dev_exit_unlock; =20 + /* initialise the cscfg_mgr structure */ + INIT_LIST_HEAD(&cscfg_mgr->csdev_desc_list); + INIT_LIST_HEAD(&cscfg_mgr->feat_desc_list); + INIT_LIST_HEAD(&cscfg_mgr->config_desc_list); + INIT_LIST_HEAD(&cscfg_mgr->load_order_list); + atomic_set(&cscfg_mgr->sys_active_cnt, 0); + /* setup the device */ dev =3D cscfg_device(); dev->release =3D cscfg_dev_release; @@ -1056,17 +1086,73 @@ static int cscfg_create_device(void) return err; } =20 -static void cscfg_clear_device(void) +/* + * Loading and unloading is generally on user discretion. + * If exiting due to coresight module unload, we need to unload any config= urations that remain, + * before we unregister the configfs intrastructure. + * + * Do this by walking the load_owner list and taking appropriate action, d= epending on the load + * owner type. + */ +static void cscfg_unload_cfgs_on_exit(void) { - struct cscfg_config_desc *cfg_desc; + struct cscfg_load_owner_info *owner_info =3D NULL; =20 + /* + * grab the mutex - even though we are exiting, some configfs files + * may still be live till we dump them, so ensure list data is + * protected from a race condition. + */ mutex_lock(&cscfg_mutex); - list_for_each_entry(cfg_desc, &cscfg_mgr->config_desc_list, item) { - etm_perf_del_symlink_cscfg(cfg_desc); + while (!list_empty(&cscfg_mgr->load_order_list)) { + + /* remove in reverse order of loading */ + owner_info =3D list_last_entry(&cscfg_mgr->load_order_list, + struct cscfg_load_owner_info, item); + + /* action according to type */ + switch (owner_info->type) { + case CSCFG_OWNER_PRELOAD: + /* + * preloaded descriptors are statically allocated in + * this module - just need to unload dynamic items from + * csdev lists, and remove from configfs directories. + */ + pr_info("cscfg: unloading preloaded configurations\n"); + break; + + case CSCFG_OWNER_MODULE: + /* + * this is an error - the loadable module must have been unloaded prior + * to the coresight module unload. Therefore that module has not + * correctly unloaded configs in its own exit code. + * Nothing to do other than emit an error string as the static descript= or + * references we need to unload will have disappeared with the module. + */ + pr_err("cscfg: ERROR: prior module failed to unload configuration\n"); + goto list_remove; + } + + /* remove from configfs - outside the scope of the list mutex */ + mutex_unlock(&cscfg_mutex); + cscfg_fs_unregister_cfgs_feats(owner_info); + mutex_lock(&cscfg_mutex); + + /* Next unload from csdev lists. */ + cscfg_unload_owned_cfgs_feats(owner_info); + +list_remove: + /* remove from load order list */ + list_del(&owner_info->item); } + mutex_unlock(&cscfg_mutex); +} + +static void cscfg_clear_device(void) +{ + cscfg_unload_cfgs_on_exit(); cscfg_configfs_release(cscfg_mgr); device_unregister(cscfg_device()); - mutex_unlock(&cscfg_mutex); } =20 /* Initialise system config management API device */ @@ -1074,20 +1160,16 @@ int __init cscfg_init(void) { int err =3D 0; =20 + /* create the device and init cscfg_mgr */ err =3D cscfg_create_device(); if (err) return err; =20 + /* initialise configfs subsystem */ err =3D cscfg_configfs_init(cscfg_mgr); if (err) goto exit_err; =20 - INIT_LIST_HEAD(&cscfg_mgr->csdev_desc_list); - INIT_LIST_HEAD(&cscfg_mgr->feat_desc_list); - INIT_LIST_HEAD(&cscfg_mgr->config_desc_list); - INIT_LIST_HEAD(&cscfg_mgr->load_order_list); - atomic_set(&cscfg_mgr->sys_active_cnt, 0); - /* preload built-in configurations */ err =3D cscfg_preload(THIS_MODULE); if (err) --=20 2.35.1