linux-kernel - [PATCH 1/3] can: mcp251xfd: mcp251xfd_remove(): fix order of unregistration calls

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Message-Id: <20250502-can-rx-offload-del-v1-1-59a9b131589d@pengutronix.de>
Date: Fri, 02 May 2025 16:13:44 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
 Thomas Kopp <thomas.kopp@...rochip.com>, 
 Vincent Mailhol <mailhol.vincent@...adoo.fr>, kernel@...gutronix.de, 
 Heiko Stuebner <heiko@...ech.de>, 
 Chandrasekar Ramakrishnan <rcsekar@...sung.com>, 
 Markus Schneider-Pargmann <msp@...libre.com>
Cc: linux-can@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org, 
 Marc Kleine-Budde <mkl@...gutronix.de>, stable@...r.kernel.org
Subject: [PATCH 1/3] can: mcp251xfd: mcp251xfd_remove(): fix order of
 unregistration calls

If a driver is removed, the driver framework invokes the driver's
remove callback. A CAN driver's remove function calls
unregister_candev(), which calls net_device_ops::ndo_stop further down
in the call stack for interfaces which are in the "up" state.

With the mcp251xfd driver the removal of the module causes the
following warning:

| WARNING: CPU: 0 PID: 352 at net/core/dev.c:7342 __netif_napi_del_locked+0xc8/0xd8

as can_rx_offload_del() deletes the NAPI, while it is still active,
because the interface is still up.

To fix the warning, first unregister the network interface, which
calls net_device_ops::ndo_stop, which disables the NAPI, and then call
can_rx_offload_del().

Fixes: 55e5b97f003e ("can: mcp25xxfd: add driver for Microchip MCP25xxFD SPI CAN")
Cc: stable@...r.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
index 3bc56517fe7a..dd0b3fb42f1b 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
@@ -2174,8 +2174,8 @@ static void mcp251xfd_remove(struct spi_device *spi)
 	struct mcp251xfd_priv *priv = spi_get_drvdata(spi);
 	struct net_device *ndev = priv->ndev;
 
-	can_rx_offload_del(&priv->offload);
 	mcp251xfd_unregister(priv);
+	can_rx_offload_del(&priv->offload);
 	spi->max_speed_hz = priv->spi_max_speed_hz_orig;
 	free_candev(ndev);
 }

-- 
2.47.2