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 A4885C2FC0F for ; Thu, 17 Aug 2023 02:34:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347625AbjHQCdn (ORCPT ); Wed, 16 Aug 2023 22:33:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41460 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235022AbjHQCdS (ORCPT ); Wed, 16 Aug 2023 22:33:18 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 97900270C; Wed, 16 Aug 2023 19:33:16 -0700 (PDT) Received: from kwepemi500012.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4RR89259nMzNmyn; Thu, 17 Aug 2023 10:29:42 +0800 (CST) Received: from [10.67.110.108] (10.67.110.108) by kwepemi500012.china.huawei.com (7.221.188.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Thu, 17 Aug 2023 10:33:14 +0800 Message-ID: Date: Thu, 17 Aug 2023 10:33:13 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.11.2 Subject: Re: [PATCH v2] cpufreq: cppc: Set fie_disabled to FIE_DISABLED if fails to create kworker_fie To: Viresh Kumar CC: , , References: <20230816094938.862186-1-liaochang1@huawei.com> <20230816103731.qwx3j3rmwyszq45j@vireshk-i7> From: "Liao, Chang" In-Reply-To: <20230816103731.qwx3j3rmwyszq45j@vireshk-i7> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.110.108] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemi500012.china.huawei.com (7.221.188.12) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2023/8/16 18:37, Viresh Kumar 写道: > On 16-08-23, 09:49, Liao Chang wrote: >> The function cppc_freq_invariance_init() may failed to create >> kworker_fie, make it more robust by setting fie_disabled to FIE_DISBALED >> to prevent an invalid pointer dereference in kthread_destroy_worker(), >> which called from cppc_freq_invariance_exit(). >> >> Link: https://lore.kernel.org/all/20230816034630.a4hvsj373q6aslk3@vireshk-i7/ >> >> Signed-off-by: Liao Chang >> --- >> drivers/cpufreq/cppc_cpufreq.c | 28 ++++++++++++++++------------ >> 1 file changed, 16 insertions(+), 12 deletions(-) >> >> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c >> index 022e3555407c..bff4cde06083 100644 >> --- a/drivers/cpufreq/cppc_cpufreq.c >> +++ b/drivers/cpufreq/cppc_cpufreq.c >> @@ -220,6 +220,15 @@ static void cppc_cpufreq_cpu_fie_exit(struct cpufreq_policy *policy) >> } >> } >> >> +static void cppc_freq_invariance_exit(void) >> +{ >> + if (fie_disabled) >> + return; >> + >> + kthread_destroy_worker(kworker_fie); >> + kworker_fie = NULL; >> +} >> + >> static void __init cppc_freq_invariance_init(void) >> { >> struct sched_attr attr = { >> @@ -249,27 +258,22 @@ static void __init cppc_freq_invariance_init(void) >> return; >> >> kworker_fie = kthread_create_worker(0, "cppc_fie"); >> - if (IS_ERR(kworker_fie)) >> + if (IS_ERR(kworker_fie)) { >> + pr_warn("%s: failed to create kworker_fie: %ld\n", __func__, >> + PTR_ERR(kworker_fie)); >> + fie_disabled = FIE_DISABLED; >> return; >> + } >> >> ret = sched_setattr_nocheck(kworker_fie->task, &attr); >> if (ret) { >> pr_warn("%s: failed to set SCHED_DEADLINE: %d\n", __func__, >> ret); >> - kthread_destroy_worker(kworker_fie); >> - return; >> + cppc_freq_invariance_exit(); > > I don't really like this change, there aren't a lot of things that we > need to do here on cleanup, but just kthread_destroy_worker(). Calling > it directly makes more sense I guess. OK，I will simplify code in next revisoin. > >> + fie_disabled = FIE_DISABLED; >> } >> } >> >> -static void cppc_freq_invariance_exit(void) >> -{ >> - if (fie_disabled) >> - return; >> - >> - kthread_destroy_worker(kworker_fie); > >> - kworker_fie = NULL; > > I don't see the point of this line. Probably it can be dropped. I agree with you, when fie_disbaled is set to FIE_DISABLED and kthred_destroy_worker() is called, the driver has no chance to access the invalid kworker_fie pointer. Thanks. > >> -} >> - >> #else >> static inline void cppc_cpufreq_cpu_fie_init(struct cpufreq_policy *policy) >> { >> -- >> 2.34.1 > -- BR Liao, Chang