Re: [PATCH 3/4] PM / Domains: Search for the CPU device outside the genpd lock

Viresh Kumar
2019-04-25T10:17:21Z

On 25-04-19, 11:04, Ulf Hansson wrote:
> While attaching/detaching a device to a PM domain (genpd) that has the
> GENPD_FLAG_CPU_DOMAIN set, genpd iterates the cpu_possible_mask to check
> whether the device corresponds to a CPU. This iteration is done while
> holding the genpd's lock, which is unnecessary. Let's avoid the locking,
> by restructuring the corresponding code a bit.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
> drivers/base/power/domain.c | 52 +++++++++++++++++++------------------
> 1 file changed, 27 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 93298b7db408..da1c99178943 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -1450,8 +1450,8 @@ static void genpd_free_dev_data(struct device *dev,
> dev_pm_put_subsys_data(dev);
> }
>
> -static void __genpd_update_cpumask(struct generic_pm_domain *genpd,
> - int cpu, bool set, unsigned int depth)
> +static void genpd_update_cpumask(struct generic_pm_domain *genpd,
> + int cpu, bool set, unsigned int depth)
> {
> struct gpd_link *link;
>
> @@ -1462,7 +1462,7 @@ static void __genpd_update_cpumask(struct generic_pm_domain *genpd,
> struct generic_pm_domain *master = link->master;
>
> genpd_lock_nested(master, depth + 1);
> - __genpd_update_cpumask(master, cpu, set, depth + 1);
> + genpd_update_cpumask(master, cpu, set, depth + 1);
> genpd_unlock(master);
> }
>
> @@ -1472,38 +1472,37 @@ static void __genpd_update_cpumask(struct generic_pm_domain *genpd,
> cpumask_clear_cpu(cpu, genpd->cpus);
> }
>
> -static void genpd_update_cpumask(struct generic_pm_domain *genpd,
> - struct device *dev, bool set)
> +static void genpd_set_cpumask(struct generic_pm_domain *genpd, int cpu)
> +{
> + if (cpu >= 0)
> + genpd_update_cpumask(genpd, cpu, true, 0);
> +}
> +
> +static void genpd_clear_cpumask(struct generic_pm_domain *genpd, int cpu)
> +{
> + if (cpu >= 0)
> + genpd_update_cpumask(genpd, cpu, false, 0);
> +}
> +
> +static int genpd_get_cpu(struct generic_pm_domain *genpd, struct device *dev)
> {
> int cpu;
>
> if (!genpd_is_cpu_domain(genpd))
> - return;
> + return -1;
>
> for_each_possible_cpu(cpu) {
> - if (get_cpu_device(cpu) == dev) {
> - __genpd_update_cpumask(genpd, cpu, set, 0);
> - return;
> - }
> + if (get_cpu_device(cpu) == dev)
> + return cpu;
> }
> -}
>
> -static void genpd_set_cpumask(struct generic_pm_domain *genpd,
> - struct device *dev)
> -{
> - genpd_update_cpumask(genpd, dev, true);
> -}
> -
> -static void genpd_clear_cpumask(struct generic_pm_domain *genpd,
> - struct device *dev)
> -{
> - genpd_update_cpumask(genpd, dev, false);
> + return -1;
> }
>
> static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev)
> {
> struct generic_pm_domain_data *gpd_data;
> - int ret;
> + int ret, cpu;
>
> dev_dbg(dev, "%s()\n", __func__);
>
> @@ -1514,13 +1513,15 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev)
> if (IS_ERR(gpd_data))
> return PTR_ERR(gpd_data);
>
> + cpu = genpd_get_cpu(genpd, dev);
> +
> ret = genpd->attach_dev ? genpd->attach_dev(genpd, dev) : 0;
> if (ret)
> goto out;
>
> genpd_lock(genpd);
>
> - genpd_set_cpumask(genpd, dev);
> + genpd_set_cpumask(genpd, cpu);
> dev_pm_domain_set(dev, &genpd->domain);
>
> genpd->device_count++;
> @@ -1560,13 +1561,14 @@ static int genpd_remove_device(struct generic_pm_domain *genpd,
> {
> struct generic_pm_domain_data *gpd_data;
> struct pm_domain_data *pdd;
> - int ret = 0;
> + int cpu, ret = 0;
>
> dev_dbg(dev, "%s()\n", __func__);
>
> pdd = dev->power.subsys_data->domain_data;
> gpd_data = to_gpd_data(pdd);
> dev_pm_qos_remove_notifier(dev, &gpd_data->nb);
> + cpu = genpd_get_cpu(genpd, dev);
>
> genpd_lock(genpd);
>
> @@ -1578,7 +1580,7 @@ static int genpd_remove_device(struct generic_pm_domain *genpd,
> genpd->device_count--;
> genpd->max_off_time_changed = true;
>
> - genpd_clear_cpumask(genpd, dev);
> + genpd_clear_cpumask(genpd, cpu);
> dev_pm_domain_set(dev, NULL);
>
> list_del_init(&pdd->list_node);

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

--
viresh