linux-kernel - [PATCH 3.16 146/370] PM / devfreq: Fix the bug of devfreq_add

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Date:   Fri, 10 Mar 2017 11:46:22 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Chanwoo Choi" <cw00.choi@...sung.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 3.16 146/370] PM / devfreq: Fix the bug of devfreq_add_device
 when governor is NULL

3.16.42-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Chanwoo Choi <cw00.choi@...sung.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.choi@...sung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/devfreq/devfreq.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -502,11 +502,16 @@ 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__);