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SubjectRe: [PATCH 2/11] cpufreq: governor: Use common mutex for dbs_data protection
On 02/03/2016 03:16 PM, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Every governor relying on the common code in cpufreq_governor.c
> has to provide its own mutex in struct common_dbs_data. However,
> those mutexes are never used at the same time and doing it this
> way makes it rather difficult to follow the code. Moreover,
> if two governor modules are loaded we end up with two mutexes
> used for the same purpose one at a time.
>
> Introduce a single common mutex for that instead and drop the
> mutex field from struct common_dbs_data. That at least will
> ensure that the mutex is always present and initialized regardless
> of what the particular governors do.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> drivers/cpufreq/cpufreq_conservative.c | 1 -
> drivers/cpufreq/cpufreq_governor.c | 7 +++++--
> drivers/cpufreq/cpufreq_governor.h | 6 +-----
> drivers/cpufreq/cpufreq_ondemand.c | 5 ++---
> 4 files changed, 8 insertions(+), 11 deletions(-)
>
> Index: linux-pm/drivers/cpufreq/cpufreq_governor.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/cpufreq_governor.c
> +++ linux-pm/drivers/cpufreq/cpufreq_governor.c
> @@ -22,6 +22,9 @@
>
> #include "cpufreq_governor.h"
>
> +DEFINE_MUTEX(dbs_data_mutex);
> +EXPORT_SYMBOL_GPL(dbs_data_mutex);
> +
> static struct attribute_group *get_sysfs_attr(struct dbs_data *dbs_data)
> {
> if (have_governor_per_policy())
> @@ -542,7 +545,7 @@ int cpufreq_governor_dbs(struct cpufreq_
> int ret;
>
> /* Lock governor to block concurrent initialization of governor */
> - mutex_lock(&cdata->mutex);
> + mutex_lock(&dbs_data_mutex);
>
> if (have_governor_per_policy())
> dbs_data = policy->governor_data;
> @@ -575,7 +578,7 @@ int cpufreq_governor_dbs(struct cpufreq_
> }
>
> unlock:
> - mutex_unlock(&cdata->mutex);
> + mutex_unlock(&dbs_data_mutex);
>
> return ret;
> }
> Index: linux-pm/drivers/cpufreq/cpufreq_governor.h
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/cpufreq_governor.h
> +++ linux-pm/drivers/cpufreq/cpufreq_governor.h
> @@ -223,11 +223,6 @@ struct common_dbs_data {
>
> /* Governor specific ops, see below */
> void *gov_ops;
> -
> - /*
> - * Protects governor's data (struct dbs_data and struct common_dbs_data)
> - */
> - struct mutex mutex;
> };
>
> /* Governor Per policy data */
> @@ -272,6 +267,7 @@ static ssize_t show_sampling_rate_min_go
> return sprintf(buf, "%u\n", dbs_data->min_sampling_rate); \
> }
>
> +extern struct mutex dbs_data_mutex;
> extern struct mutex cpufreq_governor_lock;
> void gov_set_update_util(struct cpu_common_dbs_info *shared,
> unsigned int delay_us);
> Index: linux-pm/drivers/cpufreq/cpufreq_ondemand.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/cpufreq_ondemand.c
> +++ linux-pm/drivers/cpufreq/cpufreq_ondemand.c
> @@ -251,7 +251,7 @@ static void update_sampling_rate(struct
> /*
> * Lock governor so that governor start/stop can't execute in parallel.
> */
> - mutex_lock(&od_dbs_cdata.mutex);
> + mutex_lock(&dbs_data_mutex);
>
> cpumask_copy(&cpumask, cpu_online_mask);
>
> @@ -304,7 +304,7 @@ static void update_sampling_rate(struct
> }
> }
>
> - mutex_unlock(&od_dbs_cdata.mutex);
> + mutex_unlock(&dbs_data_mutex);
> }
>
> static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
> @@ -550,7 +550,6 @@ static struct common_dbs_data od_dbs_cda
> .gov_ops = &od_ops,
> .init = od_init,
> .exit = od_exit,
> - .mutex = __MUTEX_INITIALIZER(od_dbs_cdata.mutex),
> };
>
> static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
> Index: linux-pm/drivers/cpufreq/cpufreq_conservative.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/cpufreq_conservative.c
> +++ linux-pm/drivers/cpufreq/cpufreq_conservative.c
> @@ -368,7 +368,6 @@ static struct common_dbs_data cs_dbs_cda
> .gov_check_cpu = cs_check_cpu,
> .init = cs_init,
> .exit = cs_exit,
> - .mutex = __MUTEX_INITIALIZER(cs_dbs_cdata.mutex),
> };
>
> static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
>
> --
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>


Acked-by: Saravana Kannan <skannan@codeaurora.org>


--
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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