[PATCH 4.9 112/130] PM / devfreq: Fix the bug of devfreq_add_device when governor is NULL

[Greg Kroah-Hartman]

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

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

From: Chanwoo Choi <cw00.c...@samsung.com>

commit 73613b16cb5c5d5a659fc8832eff99eead3f9afb upstream.

This patch fixes the bug of devfreq_add_device(). The devfreq device must
have the default governor. If find_devfreq_governor() returns error,
devfreq_add_device() fail to add the devfreq instance.

Fixes: 1b5c1be2c88e (PM / devfreq: map devfreq drivers to governor using name)
Signed-off-by: Chanwoo Choi <cw00.c...@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/devfreq/devfreq.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -593,11 +593,16 @@ struct devfreq *devfreq_add_device(struc
        list_add(&devfreq->node, &devfreq_list);
 
        governor = find_devfreq_governor(devfreq->governor_name);
-       if (!IS_ERR(governor))
-               devfreq->governor = governor;
-       if (devfreq->governor)
-               err = devfreq->governor->event_handler(devfreq,
-                                       DEVFREQ_GOV_START, NULL);
+       if (IS_ERR(governor)) {
+               dev_err(dev, "%s: Unable to find governor for the device\n",
+                       __func__);
+               err = PTR_ERR(governor);
+               goto err_init;
+       }
+
+       devfreq->governor = governor;
+       err = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_START,
+                                               NULL);
        if (err) {
                dev_err(dev, "%s: Unable to start governor for the device\n",
                        __func__);