From mboxrd@z Thu Jan 1 00:00:00 1970 From: Prarit Bhargava Subject: Re: [PATCH 5/5] cpufreq, add BUG() messages in critical paths to aid debugging failures Date: Tue, 11 Nov 2014 07:18:40 -0500 Message-ID: <5461FEA0.5070706@redhat.com> References: <1415199239-19019-1-git-send-email-prarit@redhat.com> <1415199239-19019-6-git-send-email-prarit@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:36946 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751022AbaKKMSw (ORCPT ); Tue, 11 Nov 2014 07:18:52 -0500 In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Viresh Kumar Cc: Linux Kernel Mailing List , =?UTF-8?B?Um9iZXJ0IFNjaMO2bmU=?= , Stephen Boyd , "Rafael J. Wysocki" , "linux-pm@vger.kernel.org" On 11/10/2014 11:23 PM, Viresh Kumar wrote: > On 5 November 2014 20:23, Prarit Bhargava wrote: >> diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c >> index b1ee597..f158882 100644 >> --- a/drivers/cpufreq/cpufreq_governor.c >> +++ b/drivers/cpufreq/cpufreq_governor.c >> @@ -161,9 +161,18 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu) >> EXPORT_SYMBOL_GPL(dbs_check_cpu); >> >> static inline void __gov_queue_work(int cpu, struct dbs_data *dbs_data, >> - unsigned int delay) >> + unsigned int delay, >> + struct cpufreq_policy *policy) >> { >> - struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu); > > I will let it crash right here instead of additional code :) the problem is tht the userful information is the values of initialized, enabled, and what the event was :( in every case i ended up needing the values. > >> @@ -258,7 +268,13 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy, >> - WARN_ON(!dbs_data && (event != CPUFREQ_GOV_POLICY_INIT)); >> + if (!dbs_data && (event != CPUFREQ_GOV_POLICY_INIT)) { >> + pr_emerg("governor_data is NULL but governor %s is initialized = %d [governor_enabled = %d event = %u]\n", >> + policy->governor->name, >> + atomic_read(&policy->governor->initialized), >> + policy->governor_enabled, event); >> + BUG(); > > How is the BUG better than the WARN here ? > we null pointer panic later on, and again the useful values are the ones displayed. >> switch (event) { >> case CPUFREQ_GOV_POLICY_INIT: >> @@ -329,6 +345,12 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy, >> case CPUFREQ_GOV_POLICY_EXIT: >> mutex_lock(&dbs_data->usage_count_mutex); >> if (atomic_dec_and_test(&dbs_data->usage_count)) { >> + if (atomic_read(&policy->governor->initialized) > 1) { > > Isn't this wrong? Consider 4 CPUs with separate clock line and have set > governor-per-policy to true. EXIT will be called for every CPU hotplug and > initialized will be 4 initially.. > > Or I am still vacation lag'd ? :) oh, is that right? i'll look into that. P. > >> + pr_emerg("Removing governor %s but initialized = %d, dbs_data->usage_count = 0\n", >> + policy->governor->name, >> + atomic_read(&policy->governor->initialized)); >> + BUG(); >> + } >> sysfs_remove_group(get_governor_parent_kobj(policy), >> get_sysfs_attr(dbs_data)); >> >> -- >> 1.7.9.3 >>