PM / Domains: Allocate memory outside domain locks

In preparation for supporting IRQ-safe domains, allocate domain data
outside the domain locks. These functions are not called in an atomic
context, so we can always allocate memory using GFP_KERNEL. By
allocating memory before the locks, we can safely lock the domain using
spinlocks instead of mutexes.
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/domain.c

@@ -1311,13 +1311,17 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
 			   struct generic_pm_domain *subdomain)
 {
-	struct gpd_link *link;
+	struct gpd_link *link, *itr;
 	int ret = 0;
 
 	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(subdomain)
 	    || genpd == subdomain)
 		return -EINVAL;
 
+	link = kzalloc(sizeof(*link), GFP_KERNEL);
+	if (!link)
+		return -ENOMEM;
+
 	mutex_lock(&genpd->lock);
 	mutex_lock_nested(&subdomain->lock, SINGLE_DEPTH_NESTING);
 
@@ -1327,18 +1331,13 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
 		goto out;
 	}
 
-	list_for_each_entry(link, &genpd->master_links, master_node) {
-		if (link->slave == subdomain && link->master == genpd) {
+	list_for_each_entry(itr, &genpd->master_links, master_node) {
+		if (itr->slave == subdomain && itr->master == genpd) {
 			ret = -EINVAL;
 			goto out;
 		}
 	}
 
-	link = kzalloc(sizeof(*link), GFP_KERNEL);
-	if (!link) {
-		ret = -ENOMEM;
-		goto out;
-	}
 	link->master = genpd;
 	list_add_tail(&link->master_node, &genpd->master_links);
 	link->slave = subdomain;
@@ -1349,7 +1348,8 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
  out:
 	mutex_unlock(&subdomain->lock);
 	mutex_unlock(&genpd->lock);
-
+	if (ret)
+		kfree(link);
 	return ret;
 }