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 8AE22C433EF for ; Fri, 17 Jun 2022 19:08:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237702AbiFQTIr (ORCPT ); Fri, 17 Jun 2022 15:08:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57796 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237770AbiFQTIq (ORCPT ); Fri, 17 Jun 2022 15:08:46 -0400 Received: from mail-pg1-x531.google.com (mail-pg1-x531.google.com [IPv6:2607:f8b0:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD3A5562D8; Fri, 17 Jun 2022 12:08:44 -0700 (PDT) Received: by mail-pg1-x531.google.com with SMTP id f65so4782519pgc.7; Fri, 17 Jun 2022 12:08:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=j41E/BYoRqjAFP436187RxcFJdtJLeDsuRyt74Icg5Y=; b=KAt/ZwIW6GKOk2RApSdAlLE9w/HUp3vrGRdYs6vuAfZyTRi008JVB0cQOEnfvn4GfV EfZaBz2oup74Sbuv+ci8AjajLNlStT4KI74+q8hh6GcNfH14P6EA4fqLQhNFErCnxcI4 mnWMYhvPo63tmos4CoENDr/K+TJ8rvQiFdDtW81B9CQvWqJ4IUXP63QrblMccCHavw5D 2G/gMYyKW0AvKJfWAWH26w286QKQPPfSbdJhtib2r3E5lZod7kFFiU4wAyTtBb6R8Mm1 qehpuyTAF/AYJgwXTQF49T407noTHjRhS+ZSfUUk7lxVgVncOStzn4rh3uui/1Cm9ihK SPOg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=j41E/BYoRqjAFP436187RxcFJdtJLeDsuRyt74Icg5Y=; b=N6RinlXpzus7smzOJTit1HO0+1IQh5fkpOcC0n6taEYLIwr611NwRJCPsLR37tFCo7 Gg3u+4nVxvY2LZ2CejNbkvmFE2DHVZ1tHSRQch64QdXcaLb9D2A598OGX3MuymJbvEni qEzt6+jIWswe5aFHmClDgBophzJLP1FgpuyplpFOjfioI2hyanEADWYIRaX+v/iKH55J 9Wr9fjCl2lukE/wUVuKImQqdf9LfKo3cieUEumKHOTqgb2P1GsYwOCdJ1daakhkzXOfp iCztGqkhjx4jEiCkmlRP8b+/+ju+bJDDcqYKU8AcKdnhUWbrOuLjL4LXSFjMpUHdii/C BLbA== X-Gm-Message-State: AJIora8lnpDZc7oBCCjTwnkiQSO1YQFj+/KBE+ogOYIe8WoI4irBJpOC D6QrDx6xvgiQniV6bnY3TUovWyYDlrg= X-Google-Smtp-Source: AGRyM1ttAZVg0K9w9XHm96HKWsCLC6j8iniymytPCQmXG79ZrpEgSUP/964Q9fbkjz0kHvDC/xMRZg== X-Received: by 2002:aa7:92d2:0:b0:51b:4d60:6475 with SMTP id k18-20020aa792d2000000b0051b4d606475mr11560802pfa.73.1655492924171; Fri, 17 Jun 2022 12:08:44 -0700 (PDT) Received: from [172.30.1.37] ([14.32.163.5]) by smtp.gmail.com with ESMTPSA id g4-20020a17090a67c400b001ec7ba41fe7sm1302753pjm.48.2022.06.17.12.08.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 17 Jun 2022 12:08:43 -0700 (PDT) Message-ID: <8ec38d8c-2ece-dfbb-8435-5963d7e80049@gmail.com> Date: Sat, 18 Jun 2022 04:08:35 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH v4 2/4] PM / devfreq: Fix kernel warning with cpufreq passive register fail Content-Language: en-US To: Ansuel Smith Cc: MyungJoo Ham , Kyungmin Park , Chanwoo Choi , Sibi Sankar , Saravana Kannan , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220614230950.426-1-ansuelsmth@gmail.com> <20220614230950.426-3-ansuelsmth@gmail.com> <5848a10e-e5bf-108f-3e3e-15e16332922d@gmail.com> <62a9af8f.1c69fb81.56ead.2c48@mx.google.com> From: Chanwoo Choi In-Reply-To: <62a9af8f.1c69fb81.56ead.2c48@mx.google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 22. 6. 15. 18:20, Ansuel Smith wrote: > On Wed, Jun 15, 2022 at 04:11:13PM +0900, Chanwoo Choi wrote: >> On 22. 6. 15. 08:09, Christian 'Ansuel' Marangi wrote: >>> When the cpufreq passive register path from the passive governor fails, >>> the cpufreq_passive_unregister is called and a kernel WARNING is always >>> reported. >>> This is caused by the fact that the devfreq driver already call the >>> governor unregister with the GOV_STOP, for this reason the second >>> cpufreq_passive_unregister always return error and a WARN is printed >>> from the WARN_ON function. >>> Remove the unregister call from the error handling of the cpufreq register >>> notifier as it's fundamentally wrong and already handled by the devfreq >>> core code. If possible, could you make the patch description more simply? >>> >>> Fixes: a03dacb0316f ("PM / devfreq: Add cpu based scaling support to passive governor") >>> Signed-off-by: Christian 'Ansuel' Marangi >>> --- >>> drivers/devfreq/governor_passive.c | 1 - >>> 1 file changed, 1 deletion(-) >>> >>> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c >>> index 95de336f20d5..dcc9dd518197 100644 >>> --- a/drivers/devfreq/governor_passive.c >>> +++ b/drivers/devfreq/governor_passive.c >>> @@ -331,7 +331,6 @@ static int cpufreq_passive_register_notifier(struct devfreq *devfreq) >>> err_put_policy: >>> cpufreq_cpu_put(policy); >>> err: >>> - WARN_ON(cpufreq_passive_unregister_notifier(devfreq)); >>> >>> return ret; >>> } >> >> I think that it is necessary to free the resource when error happen. > > Thing is that it should not be done in the register. Following the flow > of the devfreq core code, if a gov fails to START, the gov STOP is > called and we correctly free our resources. In the current > implementation we call the free 2 times and the second time will always > print error as the notifier is already unregistered. > >> Also, after merging the your patch1, I think that cpufreq_passive_unregister_notifier(devfreq) >> will not return error. Instead, just 0 for success. > > With path1 we removed the error with the parent_cpu_data deletion but > the unregister error is still there. > >> >> Instead, 'err_free_cpu_data' and 'err_put_policy' goto statement are wrong exception >> handling. If fix the exception handling code in cpufreq_passive_register_notifier >> as following and with your patch1, I'll handle the resource for free/un-registration >> when error happen during cpufreq_passive_register_notifier. >> > > Don't know the main problem here is calling unregister 2 times. Ah. I understood. To fix the error path handling with unregister function is called twice, I think that need to to fix it as following: diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c index a35b39ac656c..8f38a63beefc 100644 --- a/drivers/devfreq/governor_passive.c +++ b/drivers/devfreq/governor_passive.c @@ -289,22 +289,25 @@ static int cpufreq_passive_register_notifier(struct devfreq *devfreq) parent_cpu_data = kzalloc(sizeof(*parent_cpu_data), GFP_KERNEL); if (!parent_cpu_data) { + cpufreq_cpu_put(policy); ret = -ENOMEM; - goto err_put_policy; + goto err; } cpu_dev = get_cpu_device(cpu); if (!cpu_dev) { dev_err(dev, "failed to get cpu device\n"); + cpufreq_cpu_put(policy); ret = -ENODEV; - goto err_free_cpu_data; + goto err; } opp_table = dev_pm_opp_get_opp_table(cpu_dev); if (IS_ERR(opp_table)) { dev_err(dev, "failed to get opp_table of cpu%d\n", cpu); + cpufreq_cpu_put(policy); ret = PTR_ERR(opp_table); - goto err_free_cpu_data; + goto err; } parent_cpu_data->dev = cpu_dev; @@ -324,15 +327,7 @@ static int cpufreq_passive_register_notifier(struct devfreq *devfreq) if (ret) dev_err(dev, "failed to update the frequency\n"); - return ret; - -err_free_cpu_data: - kfree(parent_cpu_data); -err_put_policy: - cpufreq_cpu_put(policy); err: - WARN_ON(cpufreq_passive_unregister_notifier(devfreq)); - return ret; } -- Best Regards, Samsung Electronics Chanwoo Choi