linux-kernel - [PATCH 5.4 081/158] can: flexcan: fix failure handling of pm_runtime_get

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Message-Id: <20201123121823.838877636@linuxfoundation.org>
Date:   Mon, 23 Nov 2020 13:21:49 +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, Zhang Qilong <zhangqilong3@...wei.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 081/158] can: flexcan: fix failure handling of pm_runtime_get_sync()

From: Zhang Qilong <zhangqilong3@...wei.com>

[ Upstream commit b7ee5bc3e1006433601a058a6a7c24c5272635f4 ]

pm_runtime_get_sync() will increment pm usage at first and it will resume the
device later. If runtime of the device has error or device is in inaccessible
state(or other error state), resume operation will fail. If we do not call put
operation to decrease the reference, it will result in reference leak in the
two functions flexcan_get_berr_counter() and flexcan_open().

Moreover, this device cannot enter the idle state and always stay busy or other
non-idle state later. So we should fix it through adding
pm_runtime_put_noidle().

Fixes: ca10989632d88 ("can: flexcan: implement can Runtime PM")
Signed-off-by: Zhang Qilong <zhangqilong3@...wei.com>
Link: https://lore.kernel.org/r/20201108083000.2599705-1-zhangqilong3@huawei.com
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/can/flexcan.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 130f3022d3396..b22cd8d14716a 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -614,8 +614,10 @@ static int flexcan_get_berr_counter(const struct net_device *dev,
 	int err;
 
 	err = pm_runtime_get_sync(priv->dev);
-	if (err < 0)
+	if (err < 0) {
+		pm_runtime_put_noidle(priv->dev);
 		return err;
+	}
 
 	err = __flexcan_get_berr_counter(dev, bec);
 
@@ -1282,8 +1284,10 @@ static int flexcan_open(struct net_device *dev)
 	int err;
 
 	err = pm_runtime_get_sync(priv->dev);
-	if (err < 0)
+	if (err < 0) {
+		pm_runtime_put_noidle(priv->dev);
 		return err;
+	}
 
 	err = open_candev(dev);
 	if (err)
-- 
2.27.0