From:   Pavel Skripkin <paskripkin@gmail.com>
To:     mailhol.vincent@wanadoo.fr, wg@grandegger.com, mkl@pengutronix.de,
        davem@davemloft.net, kuba@kernel.org
Cc:     linux-can@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Pavel Skripkin <paskripkin@gmail.com>
Subject: [PATCH v3] can: etas_es58x: fix error handling
Date:   Mon, 15 Nov 2021 11:37:56 +0300
Message-Id: <20211115083756.25971-1-paskripkin@gmail.com>
In-Reply-To: <YZIWT9ATzN611n43@hovoldconsulting.com>
References: <YZIWT9ATzN611n43@hovoldconsulting.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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@gmail.com>
---

Changes in v3:
	- Moved back es58x_dev->netdev[channel_idx] initialization,
	  since it's unsafe to intialize it _after_ register_candev()
	  call. Thanks to Johan Hovold <johan@kernel.org> for spotting
	  it

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 | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/usb/etas_es58x/es58x_core.c b/drivers/net/can/usb/etas_es58x/es58x_core.c
index 96a13c770e4a..41c721f2fbbe 100644
--- a/drivers/net/can/usb/etas_es58x/es58x_core.c
+++ b/drivers/net/can/usb/etas_es58x/es58x_core.c
@@ -2098,8 +2098,11 @@ static int es58x_init_netdev(struct es58x_device *es58x_dev, int channel_idx)
 	netdev->flags |= IFF_ECHO;	/* We support local echo */
 
 	ret = register_candev(netdev);
-	if (ret)
+	if (ret) {
+		free_candev(netdev);
+		es58x_dev->netdev[channel_idx] = NULL;
 		return ret;
+	}
 
 	netdev_queue_set_dql_min_limit(netdev_get_tx_queue(netdev, 0),
 				       es58x_dev->param->dql_min_limit);
-- 
2.33.1