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SubjectRe: [PATCH v4 1/2] cpufreq: change '.set_boost' to act on only one policy
Date
On Friday, May 22, 2020 5:34:35 AM CEST Xiongfeng Wang wrote:
> Macro 'for_each_active_policy()' is defined internally. To avoid some
> cpufreq driver needing this macro to iterate over all the policies in
> '.set_boost' callback, we redefine '.set_boost' to act on only one
> policy and pass the policy as an argument.
> 'cpufreq_boost_trigger_state()' iterate over all the policies to set
> boost for the system. This is preparation for adding SW BOOST support
> for CPPC.
>
> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
> Suggested-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> drivers/cpufreq/acpi-cpufreq.c | 10 ++++----
> drivers/cpufreq/cpufreq.c | 53 +++++++++++++++++++++---------------------
> include/linux/cpufreq.h | 2 +-
> 3 files changed, 34 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
> index 289e8ce..813aabf 100644
> --- a/drivers/cpufreq/acpi-cpufreq.c
> +++ b/drivers/cpufreq/acpi-cpufreq.c
> @@ -126,12 +126,14 @@ static void boost_set_msr_each(void *p_en)
> boost_set_msr(enable);
> }
>
> -static int set_boost(int val)
> +static int set_boost(struct cpufreq_policy *policy, int val)
> {
> get_online_cpus();
> - on_each_cpu(boost_set_msr_each, (void *)(long)val, 1);
> + on_each_cpu_mask(policy->cpus, boost_set_msr_each,
> + (void *)(long)val, 1);
> put_online_cpus();
> - pr_debug("Core Boosting %sabled.\n", val ? "en" : "dis");
> + pr_debug("CPU %*pbl: Core Boosting %sabled.\n",
> + cpumask_pr_args(policy->cpus), val ? "en" : "dis");
>
> return 0;
> }
> @@ -162,7 +164,7 @@ static ssize_t store_cpb(struct cpufreq_policy *policy, const char *buf,
> if (ret || val > 1)
> return -EINVAL;
>
> - set_boost(val);
> + set_boost(policy, val);
>
> return count;
> }
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index d03f250..d0d86b1 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2532,34 +2532,29 @@ void cpufreq_update_limits(unsigned int cpu)
> /*********************************************************************
> * BOOST *
> *********************************************************************/
> -static int cpufreq_boost_set_sw(int state)
> +static int cpufreq_boost_set_sw(struct cpufreq_policy *policy, int state)
> {
> - struct cpufreq_policy *policy;
> -
> - for_each_active_policy(policy) {
> - int ret;
> -
> - if (!policy->freq_table)
> - return -ENXIO;
> + int ret;
>
> - ret = cpufreq_frequency_table_cpuinfo(policy,
> - policy->freq_table);
> - if (ret) {
> - pr_err("%s: Policy frequency update failed\n",
> - __func__);
> - return ret;
> - }
> + if (!policy->freq_table)
> + return -ENXIO;
>
> - ret = freq_qos_update_request(policy->max_freq_req, policy->max);
> - if (ret < 0)
> - return ret;
> + ret = cpufreq_frequency_table_cpuinfo(policy, policy->freq_table);
> + if (ret) {
> + pr_err("%s: Policy frequency update failed\n", __func__);
> + return ret;
> }
>
> + ret = freq_qos_update_request(policy->max_freq_req, policy->max);
> + if (ret < 0)
> + return ret;
> +
> return 0;
> }
>
> int cpufreq_boost_trigger_state(int state)
> {
> + struct cpufreq_policy *policy;
> unsigned long flags;
> int ret = 0;
>
> @@ -2570,16 +2565,22 @@ int cpufreq_boost_trigger_state(int state)

AFAICS this gets called via sysfs without any cpufreq locking whatever, so
I'm not really sure what causes it to be safe with respect to CPU offline /
online, especially if the ->set_boost() callback only wants to do stuff
for CPUs that are online.

> cpufreq_driver->boost_enabled = state;
> write_unlock_irqrestore(&cpufreq_driver_lock, flags);
>
> - ret = cpufreq_driver->set_boost(state);
> - if (ret) {
> - write_lock_irqsave(&cpufreq_driver_lock, flags);
> - cpufreq_driver->boost_enabled = !state;
> - write_unlock_irqrestore(&cpufreq_driver_lock, flags);
> -
> - pr_err("%s: Cannot %s BOOST\n",
> - __func__, state ? "enable" : "disable");
> + for_each_active_policy(policy) {
> + ret = cpufreq_driver->set_boost(policy, state);
> + if (ret)
> + goto err_reset_state;
> }
>
> + return 0;
> +
> +err_reset_state:
> + write_lock_irqsave(&cpufreq_driver_lock, flags);
> + cpufreq_driver->boost_enabled = !state;
> + write_unlock_irqrestore(&cpufreq_driver_lock, flags);
> +
> + pr_err("%s: Cannot %s BOOST\n",
> + __func__, state ? "enable" : "disable");
> +
> return ret;
> }
>
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 67d5950..3494f67 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -367,7 +367,7 @@ struct cpufreq_driver {
>
> /* platform specific boost support code */
> bool boost_enabled;
> - int (*set_boost)(int state);
> + int (*set_boost)(struct cpufreq_policy *policy, int state);
> };
>
> /* flags */
>




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