linux-kernel - [PATCH v2] can: etas_es58x: fix error handling

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Message-Id: <20211115075124.17713-1-paskripkin@gmail.com>
Date:   Mon, 15 Nov 2021 10:51:24 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     mailhol.vincent@...adoo.fr, wg@...ndegger.com, mkl@...gutronix.de,
        davem@...emloft.net, kuba@...nel.org
Cc:     linux-can@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Pavel Skripkin <paskripkin@...il.com>
Subject: [PATCH v2] can: etas_es58x: fix error handling

When register_candev() fails there are 2 possible device states:
NETREG_UNINITIALIZED and NETREG_UNREGISTERED. None of them are suitable
for calling unregister_candev(), because of following checks in
unregister_netdevice_many():

	if (dev->reg_state == NETREG_UNINITIALIZED)
		WARN_ON(1);
...
	BUG_ON(dev->reg_state != NETREG_REGISTERED);

To avoid possible BUG_ON or WARN_ON let's free current netdev before
returning from es58x_init_netdev() and leave others (registered)
net devices for es58x_free_netdevs().

Fixes: 8537257874e9 ("can: etas_es58x: add core support for ETAS ES58X CAN USB interfaces")
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
---

Changes in v2:
	- Fixed Fixes: tag
	- Moved es58x_dev->netdev[channel_idx] initialization at the end
	  of the function

---
 drivers/net/can/usb/etas_es58x/es58x_core.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/usb/etas_es58x/es58x_core.c b/drivers/net/can/usb/etas_es58x/es58x_core.c
index 96a13c770e4a..b3af8f2e32ac 100644
--- a/drivers/net/can/usb/etas_es58x/es58x_core.c
+++ b/drivers/net/can/usb/etas_es58x/es58x_core.c
@@ -2091,19 +2091,22 @@ static int es58x_init_netdev(struct es58x_device *es58x_dev, int channel_idx)
 		return -ENOMEM;
 	}
 	SET_NETDEV_DEV(netdev, dev);
-	es58x_dev->netdev[channel_idx] = netdev;
 	es58x_init_priv(es58x_dev, es58x_priv(netdev), channel_idx);
 
 	netdev->netdev_ops = &es58x_netdev_ops;
 	netdev->flags |= IFF_ECHO;	/* We support local echo */
 
 	ret = register_candev(netdev);
-	if (ret)
+	if (ret) {
+		free_candev(netdev);
 		return ret;
+	}
 
 	netdev_queue_set_dql_min_limit(netdev_get_tx_queue(netdev, 0),
 				       es58x_dev->param->dql_min_limit);
 
+	es58x_dev->netdev[channel_idx] = netdev;
+
 	return ret;
 }
 
-- 
2.33.1