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

Ulf Hansson
2019-04-25T09:05:19Z

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);
--
2.17.1