Patch "PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

    PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
pm-domains-defer-dev_pm_domain_set-until-genpd-attach_dev-succeeds-if-present.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Sudeep Holla <[email protected]>
Date: Fri, 14 Jul 2017 11:51:48 +0100
Subject: PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present

From: Sudeep Holla <[email protected]>

commit 975e83cfb8dc16e7a2fdc58188c77c0c605876c2 upstream.

If the genpd->attach_dev or genpd->power_on fails, genpd_dev_pm_attach may return -EPROBE_DEFER initially. However genpd_alloc_dev_data sets the PM domain for the device unconditionally.

When subsequent attempts are made to call genpd_dev_pm_attach, it may return -EEXISTS checking dev->pm_domain without re-attempting to call attach_dev or power_on.

platform_drv_probe then attempts to call drv->probe as the return value -EEXIST != -EPROBE_DEFER, which may end up in a situation where the device is accessed without it's power domain switched on.

---
 drivers/base/power/domain.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

@@ -1188,7 +1188,6 @@ static struct generic_pm_domain_data *ge
 	}
 
 	dev->power.subsys_data->domain_data = &gpd_data->base;
-	dev->pm_domain = &genpd->domain;
 
 	spin_unlock_irq(&dev->power.lock);
 

@@ -1207,7 +1206,6 @@ static void genpd_free_dev_data(struct d
 {
 	spin_lock_irq(&dev->power.lock);
 
-	dev->pm_domain = NULL;
 	dev->power.subsys_data->domain_data = NULL;
 
 	spin_unlock_irq(&dev->power.lock);

@@ -1248,6 +1246,8 @@ int __pm_genpd_add_device(struct generic
 	if (ret)
 		goto out;
 
+	dev->pm_domain = &genpd->domain;
+
 	genpd->device_count++;
 	genpd->max_off_time_changed = true;
 

@@ -1299,6 +1299,8 @@ int pm_genpd_remove_device(struct generi
 	if (genpd->detach_dev)
 		genpd->detach_dev(genpd, dev);
 
+	dev->pm_domain = NULL;
+
 	list_del_init(&pdd->list_node);
 
 	mutex_unlock(&genpd->lock);

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/pm-domains-defer-dev_pm_domain_set-until-genpd-attach_dev-succeeds-if-present.patch