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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 C8512C433DF for ; Mon, 17 Aug 2020 17:06:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9885520716 for ; Mon, 17 Aug 2020 17:06:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597683988; bh=s9Uz8xel/PTVtq7+hr3B9WgsiuOjZDmxIlXkQ49B1oU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=IGNLEaG90Q7vGIrgWtkXctw3RcLGOojtuMnkI3AilBpddoeM29erOPg895D2uaYAP U5+K/7y6Nu7+WB/7SvIgovJvTUFzCxpLAvGUMKXbEi3NoPj5roJO+TJMmqVbG8owXt Ql4ptKlQwr44c+M1aM+lXr/WK6zBE6bE4AkSgqrU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388505AbgHQRF6 (ORCPT ); Mon, 17 Aug 2020 13:05:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:59836 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388386AbgHQQJb (ORCPT ); Mon, 17 Aug 2020 12:09:31 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B320D20729; Mon, 17 Aug 2020 16:09:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597680570; bh=s9Uz8xel/PTVtq7+hr3B9WgsiuOjZDmxIlXkQ49B1oU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=krxqFnR2NUE02DoK7i8c0sF5RBwkENv6QquJY6LcJTWCh5UiYrcbg5/TWsLaabJpm F2vFCnU9WyX4C++BFS1lfww3kAgDMj8Rki1fXSfuvssqtW+booko1t4oVrBmlcMZi0 ZaaG0QXvszI6Dze5UZY6YfDT3os2T4DBIzxi2Urg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Quentin Perret , Viresh Kumar , "Rafael J. Wysocki" Subject: [PATCH 5.4 240/270] cpufreq: Fix locking issues with governors Date: Mon, 17 Aug 2020 17:17:21 +0200 Message-Id: <20200817143807.770401962@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200817143755.807583758@linuxfoundation.org> References: <20200817143755.807583758@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Viresh Kumar commit 8cc46ae565c393f77417cb9530b1265eb50f5d2e upstream. The locking around governors handling isn't adequate currently. The list of governors should never be traversed without the locking in place. Also governor modules must not be removed while the code in them is still in use. Reported-by: Quentin Perret Signed-off-by: Viresh Kumar Cc: All applicable [ rjw: Changelog ] Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman --- drivers/cpufreq/cpufreq.c | 58 +++++++++++++++++++++++++++------------------- 1 file changed, 35 insertions(+), 23 deletions(-) --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -616,6 +616,24 @@ static struct cpufreq_governor *find_gov return NULL; } +static struct cpufreq_governor *get_governor(const char *str_governor) +{ + struct cpufreq_governor *t; + + mutex_lock(&cpufreq_governor_mutex); + t = find_governor(str_governor); + if (!t) + goto unlock; + + if (!try_module_get(t->owner)) + t = NULL; + +unlock: + mutex_unlock(&cpufreq_governor_mutex); + + return t; +} + static unsigned int cpufreq_parse_policy(char *str_governor) { if (!strncasecmp(str_governor, "performance", CPUFREQ_NAME_LEN)) @@ -635,28 +653,14 @@ static struct cpufreq_governor *cpufreq_ { struct cpufreq_governor *t; - mutex_lock(&cpufreq_governor_mutex); - - t = find_governor(str_governor); - if (!t) { - int ret; + t = get_governor(str_governor); + if (t) + return t; - mutex_unlock(&cpufreq_governor_mutex); + if (request_module("cpufreq_%s", str_governor)) + return NULL; - ret = request_module("cpufreq_%s", str_governor); - if (ret) - return NULL; - - mutex_lock(&cpufreq_governor_mutex); - - t = find_governor(str_governor); - } - if (t && !try_module_get(t->owner)) - t = NULL; - - mutex_unlock(&cpufreq_governor_mutex); - - return t; + return get_governor(str_governor); } /** @@ -810,12 +814,14 @@ static ssize_t show_scaling_available_go goto out; } + mutex_lock(&cpufreq_governor_mutex); for_each_governor(t) { if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char)) - (CPUFREQ_NAME_LEN + 2))) - goto out; + break; i += scnprintf(&buf[i], CPUFREQ_NAME_PLEN, "%s ", t->name); } + mutex_unlock(&cpufreq_governor_mutex); out: i += sprintf(&buf[i], "\n"); return i; @@ -1053,15 +1059,17 @@ static int cpufreq_init_policy(struct cp struct cpufreq_governor *def_gov = cpufreq_default_governor(); struct cpufreq_governor *gov = NULL; unsigned int pol = CPUFREQ_POLICY_UNKNOWN; + int ret; if (has_target()) { /* Update policy governor to the one used before hotplug. */ - gov = find_governor(policy->last_governor); + gov = get_governor(policy->last_governor); if (gov) { pr_debug("Restoring governor %s for cpu %d\n", policy->governor->name, policy->cpu); } else if (def_gov) { gov = def_gov; + __module_get(gov->owner); } else { return -ENODATA; } @@ -1084,7 +1092,11 @@ static int cpufreq_init_policy(struct cp return -ENODATA; } - return cpufreq_set_policy(policy, gov, pol); + ret = cpufreq_set_policy(policy, gov, pol); + if (gov) + module_put(gov->owner); + + return ret; } static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu)