linux-kernel - [PATCH 4.4 36/91] PM / Domains: defer dev_pm_domain_set() until genpd->attach

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Date:   Fri,  4 Aug 2017 16:15:32 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Sudeep Holla <sudeep.holla@....com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 4.4 36/91] PM / Domains: defer dev_pm_domain_set() until genpd->attach_dev succeeds if present

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sudeep Holla <Sudeep.Holla@....com>

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.

Fixes: f104e1e5ef57 (PM / Domains: Re-order initialization of generic_pm_domain_data)
Signed-off-by: Sudeep Holla <sudeep.holla@....com>
Acked-by: Ulf Hansson <ulf.hansson@...aro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>


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

--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -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);