[PATCH] PM / Domains: Add module ref count for each consumer

[Gustav Wiklander <gustav.wiklander@axis.com>]

From: Gustav Wiklander <gustavwi@axis.com>

Currently a pm_domain can be unloaded without regard for consumers.
This patch adds a module dependecy for every registered consumer.
Now a power domain driver can only be unloaded if no consumers are
registered.

Signed-off-by: Gustav Wiklander <gustavwi@axis.com>
---
 drivers/base/power/domain.c | 11 ++++++++++-
 include/linux/pm_domain.h   |  2 ++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 0a01df608849..80723f6d5e6b 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -1499,11 +1499,18 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	if (IS_ERR(gpd_data))
 		return PTR_ERR(gpd_data);
 
+	if (!try_module_get(genpd->owner)) {
+		ret = -ENODEV;
+		goto out;
+	}
+
 	gpd_data->cpu = genpd_get_cpu(genpd, base_dev);
 
 	ret = genpd->attach_dev ? genpd->attach_dev(genpd, dev) : 0;
-	if (ret)
+	if (ret) {
+		module_put(genpd->owner);
 		goto out;
+	}
 
 	genpd_lock(genpd);
 
@@ -1579,6 +1586,8 @@ static int genpd_remove_device(struct generic_pm_domain *genpd,
 
 	genpd_free_dev_data(dev, gpd_data);
 
+	module_put(genpd->owner);
+
 	return 0;
 
  out:
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 9ec78ee53652..777c1b30e5af 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -9,6 +9,7 @@
 #define _LINUX_PM_DOMAIN_H
 
 #include <linux/device.h>
+#include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/pm.h>
 #include <linux/err.h>
@@ -93,6 +94,7 @@ struct opp_table;
 
 struct generic_pm_domain {
 	struct device dev;
+	struct module *owner;		/* Module owner of the PM domain */
 	struct dev_pm_domain domain;	/* PM domain operations */
 	struct list_head gpd_list_node;	/* Node in the global PM domains list */
 	struct list_head master_links;	/* Links with PM domain as a master */
-- 
2.11.0