From patchwork Wed Jun 22 10:16:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Leach X-Patchwork-Id: 12890458 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 27F81CCA47D for ; Wed, 22 Jun 2022 10:19:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=T57k8HBzWI7q5BdbFmVXSNXlrM/F6PvtwAmOnEMDu3Y=; b=CcCcHbtja7w+EX 5VeMUGtTfkz48n7FyYKWLmRHQoRJGS2VDkU3toyuH3rku+GOC35YJL8KpE2xxHcvMS0DKx3WT9R0r AIvtkuTZ7OPqu2W/nYLBH+aQp7Gxlq0ZuhM0ipl+ymkYXF3LRkoUKvp7SkTT1KdrOoHXz+WqOW7NX wkjFJ87W6+JZbnydkEkfUdKar2RsOaHpEHck7B1ofmpwUOBtTbZCljm/4I88K1iHwR9NzCXatI5Iq txtaH0qsAHEw/amembU0C21BxI4rQL7G6cNZrsOLx15GU6B1Ol2Z+BIfrHOaGwAOmz7lnhOXmy8FM yhqT8jIjkH1tR0Yc36qw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o3xRO-009pZ0-Ld; Wed, 22 Jun 2022 10:18:31 +0000 Received: from mail-wr1-x42a.google.com ([2a00:1450:4864:20::42a]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o3xPQ-009oe0-M7 for linux-arm-kernel@lists.infradead.org; Wed, 22 Jun 2022 10:16:30 +0000 Received: by mail-wr1-x42a.google.com with SMTP id w17so22667373wrg.7 for ; Wed, 22 Jun 2022 03:16:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=XQYKhPzrWDpATxex5KWLiZaM+A+y+UfyX+SZUn3kS8Q=; b=kCJ0B7cUkdGMPFQhgAv1hQXecvNAYj2tbM6vRV3HLPHMHnx4lhf2vQG7epJSxZITMi ZEER1+zjQYxW0fpGm2GgXEaS27LJx1V47SIuH/0Sy77TVq+CBKihDMJCZYj+ifgAU9g1 KpdWcSCW/JrMRnZ+TG5OH4Ck39q5UOw6nv/8osfItxJq79dBlwpy1ich8bu5ybTY4ybk Vt2KEXrpwbReRPVMIx7xnvHCIkad2SBLywmKLdCAEYtRWjJ+hA90w4SgnWUGb6zWb1Xt uhvCw3mX5Moa8fSQ+eSlLyFtqWJuTvrwBjg+28v5nhkTM4FQdBitQXA3MJvCJI1CWej6 XsJQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=XQYKhPzrWDpATxex5KWLiZaM+A+y+UfyX+SZUn3kS8Q=; b=2xNpSoPIe8Zpck3XjvNBP41powVEL/aS5IomWysuZH0NgY5hT8nIQVKWR4mSzrMlj/ mAIgyesge7l2OBTkop6225WHONgIjZUtQTcEBRDKXw5GSQisasWm5TqkqlbIK9gEhthB M1tnXntrvxxnyYRTThOvbDxuOF/9fm8N0p2DMIwWohzPnF+lPd9h++gh0JbC+shLf4rn 8pkFhi7OYS4i6zNmLfd7xc1bNHhcTEQBl7KvPC1Boj4Dc/2BMn3ZeBX0zY8+mwzmqq/b D2Hvrbdqn0oErSEyAR3K6PhAMyZMBqahcs8iPQtz6vQRtnFVpcAgj0U6W5aFrhsDqgxw Qcpw== X-Gm-Message-State: AJIora/+yzgDYX1RymQ2t4BBfeoE8dByDrH7xvX+ou41m0LzElY6P9/U riKEV5HTdy8M72uX4gaxICho/9PZx+CjyA== X-Google-Smtp-Source: AGRyM1v4JEiNmiAE/GG68ZTuUBJYdmTPWDosmdN4nVUHfaiDk6GZX3M+WvIn/jRgiRXJHfrjyAI5EA== X-Received: by 2002:a5d:59a1:0:b0:219:b52d:d11b with SMTP id p1-20020a5d59a1000000b00219b52dd11bmr2575237wrr.436.1655892985132; Wed, 22 Jun 2022 03:16:25 -0700 (PDT) Received: from linaro.org ([2a00:23c5:6809:2201:546d:7d59:1703:bf96]) by smtp.gmail.com with ESMTPSA id cl10-20020a5d5f0a000000b0021b92171d28sm8850936wrb.54.2022.06.22.03.16.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Jun 2022 03:16:24 -0700 (PDT) From: Mike Leach To: linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org, suzuki.poulose@arm.com Cc: mathieu.poirier@linaro.org, leo.yan@linaro.org, Mike Leach Subject: [PATCH v4 1/2] coresight: configfs: Fix unload of configurations on module exit Date: Wed, 22 Jun 2022 11:16:20 +0100 Message-Id: <20220622101621.4312-2-mike.leach@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220622101621.4312-1-mike.leach@linaro.org> References: <20220622101621.4312-1-mike.leach@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220622_031628_820614_21A29B75 X-CRM114-Status: GOOD ( 30.19 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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. Applies to coresight/next Fixes: eb2ec49606c2 ("coresight: syscfg: Update load API for config loadable modules") Reported-by: Suzuki Poulose Signed-off-by: Mike Leach --- .../hwtracing/coresight/coresight-syscfg.c | 106 ++++++++++++++++-- 1 file changed, 95 insertions(+), 11 deletions(-) diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c index 11850fd8c3b5..9cd7d3c91d8e 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 coresight_device *csdev, vo } } +/* + * Unregister all configuration and features from configfs owned by load_owner. + * 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 == 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 == 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 owner, @@ -1022,10 +1043,13 @@ struct device *cscfg_device(void) /* Must have a release function or the kernel will complain on module unload */ static void cscfg_dev_release(struct device *dev) { + mutex_lock(&cscfg_mutex); kfree(cscfg_mgr); cscfg_mgr = NULL; + mutex_unlock(&cscfg_mutex); } + /* a device is needed to "own" some kernel elements such as sysfs entries. */ static int cscfg_create_device(void) { @@ -1042,6 +1066,13 @@ static int cscfg_create_device(void) if (!cscfg_mgr) goto create_dev_exit_unlock; + /* 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 = cscfg_device(); dev->release = cscfg_dev_release; @@ -1056,17 +1087,74 @@ static int cscfg_create_device(void) return err; } -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 configurations that remain, + * before we unregister the configfs intrastructure. + * + * Do this by walking the load_owner list and taking appropriate action, depending 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 = NULL; + /* + * 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 = 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 descriptor + * references we need to unload will have disappeared with the module. + */ + pr_err("cscfg: ERROR - a loadable module failed to " + "unload configs on exit\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); } /* Initialise system config management API device */ @@ -1074,20 +1162,16 @@ int __init cscfg_init(void) { int err = 0; + /* create the device and init cscfg_mgr */ err = cscfg_create_device(); if (err) return err; + /* initialise configfs subsystem */ err = cscfg_configfs_init(cscfg_mgr); if (err) goto exit_err; - 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 = cscfg_preload(THIS_MODULE); if (err)