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Date: Tue, 11 Nov 2014 09:53:46 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Prarit Bhargava <prarit@...hat.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Robert Schöne <robert.schoene@...dresden.de>,
Stephen Boyd <sboyd@...eaurora.org>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 5/5] cpufreq, add BUG() messages in critical paths to aid
debugging failures
On 5 November 2014 20:23, Prarit Bhargava <prarit@...hat.com> 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 :)
> @@ -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 ?
> 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 ? :)
> + 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
>
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