PM / Domains: Search for the CPU device outside the genpd lock

While attaching/detaching a device to a PM domain (genpd) with
GENPD_FLAG_CPU_DOMAIN set, genpd iterates the cpu_possible_mask to
check whether or not the device corresponds to a CPU. This iteration
is done while holding the genpd's lock, which is unnecessary.

Avoid the locking by restructuring the corresponding code a bit.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 93298b7..da1c991 100644 (file)
--- 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);