linux-kernel - [PATCH 4.9 01/91] PM / devfreq: Dont fail devfreq_dev

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Date:   Sat, 11 Jan 2020 10:48:54 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Leonard Crestez <leonard.crestez@....com>,
        Matthias Kaehlcke <mka@...omium.org>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 01/91] PM / devfreq: Dont fail devfreq_dev_release if not in list

From: Leonard Crestez <leonard.crestez@....com>

[ Upstream commit 42a6b25e67df6ee6675e8d1eaf18065bd73328ba ]

Right now devfreq_dev_release will print a warning and abort the rest of
the cleanup if the devfreq instance is not part of the global
devfreq_list. But this is a valid scenario, for example it can happen if
the governor can't be found or on any other init error that happens
after device_register.

Initialize devfreq->node to an empty list head in devfreq_add_device so
that list_del becomes a safe noop inside devfreq_dev_release and we can
continue the rest of the cleanup.

Signed-off-by: Leonard Crestez <leonard.crestez@....com>
Reviewed-by: Matthias Kaehlcke <mka@...omium.org>
Reviewed-by: Chanwoo Choi <cw00.choi@...sung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/devfreq/devfreq.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index df62e38de5f5..fb696957eb21 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -482,11 +482,6 @@ static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
 static void _remove_devfreq(struct devfreq *devfreq)
 {
 	mutex_lock(&devfreq_list_lock);
-	if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
-		mutex_unlock(&devfreq_list_lock);
-		dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
-		return;
-	}
 	list_del(&devfreq->node);
 	mutex_unlock(&devfreq_list_lock);
 
@@ -558,6 +553,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
 	devfreq->dev.parent = dev;
 	devfreq->dev.class = devfreq_class;
 	devfreq->dev.release = devfreq_dev_release;
+	INIT_LIST_HEAD(&devfreq->node);
 	devfreq->profile = profile;
 	strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 	devfreq->previous_freq = profile->initial_freq;
-- 
2.20.1