netdev - [PATCH v2] can: flexcan: fix reference count leak in flexcan ops

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Date:   Sun, 8 Nov 2020 16:30:00 +0800
From:   Zhang Qilong <zhangqilong3@...wei.com>
To:     <wg@...ndegger.com>, <mkl@...gutronix.de>, <davem@...emloft.net>,
        <kuba@...nel.org>
CC:     <linux-can@...r.kernel.org>, <netdev@...r.kernel.org>
Subject: [PATCH v2] can: flexcan: fix reference count leak in flexcan ops

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 function(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>
---
Changelog:
v2
- removed empty lines between tags.
---
 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 881799bd9c5e..c42a1ae5ee46 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -728,8 +728,10 @@ 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);
 
@@ -1654,8 +1656,10 @@ static int flexcan_open(struct net_device *dev)
 	}
 
 	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)
-- 
2.25.4