[PATCH 0/3] can: rx-offload: fix order of unregistration calls

[PATCH 0/3] can: rx-offload: fix order of unregistration calls

[Marc Kleine-Budde]

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().

All other driver using the rx-offload helper have been checked and the
same issue has been found in the rockchip and m_can driver. These have
been fixed, but only compile time tested. On the mcp251xfd the fix was
tested on hardware.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
Marc Kleine-Budde (3):
      can: mcp251xfd: mcp251xfd_remove(): fix order of unregistration calls
      can: rockchip_canfd: m_can_class_unregister: fix order of unregistration calls
      can: mcan: m_can_class_unregister: fix order of unregistration calls

 drivers/net/can/m_can/m_can.c                  | 2 +-
 drivers/net/can/rockchip/rockchip_canfd-core.c | 2 +-
 drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)
---
base-commit: ebd297a2affadb6f6f4d2e5d975c1eda18ac762d
change-id: 20250502-can-rx-offload-del-eb79379733dd

Best regards,
-- 
Marc Kleine-Budde <mkl@pengutronix.de>

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

[Marc Kleine-Budde]

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@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.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

[PATCH 2/3] can: rockchip_canfd: m_can_class_unregister: fix order of unregistration calls

[Marc Kleine-Budde]

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.

The removal of the module causes the a warning, 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: ff60bfbaf67f ("can: rockchip_canfd: add driver for Rockchip CAN-FD controller")
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/rockchip/rockchip_canfd-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/rockchip/rockchip_canfd-core.c b/drivers/net/can/rockchip/rockchip_canfd-core.c
index 7107a37da36c..c3fb3176ce42 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-core.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-core.c
@@ -937,8 +937,8 @@ static void rkcanfd_remove(struct platform_device *pdev)
 	struct rkcanfd_priv *priv = platform_get_drvdata(pdev);
 	struct net_device *ndev = priv->ndev;
 
-	can_rx_offload_del(&priv->offload);
 	rkcanfd_unregister(priv);
+	can_rx_offload_del(&priv->offload);
 	free_candev(ndev);
 }
 

-- 
2.47.2

Re: [PATCH 2/3] can: rockchip_canfd: m_can_class_unregister: fix order of unregistration calls

[Markus Schneider-Pargmann]

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On Fri May 2, 2025 at 4:13 PM CEST, Marc Kleine-Budde wrote:
> 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.
>
> The removal of the module causes the a warning, as
                                   ^^^
Minor typo here.

Otherwise this looks good to me.

Reviewed-by: Markus Schneider-Pargmann

> 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: ff60bfbaf67f ("can: rockchip_canfd: add driver for Rockchip CAN-FD controller")
> Cc: stable@vger.kernel.org
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
> ---
>  drivers/net/can/rockchip/rockchip_canfd-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/can/rockchip/rockchip_canfd-core.c b/drivers/net/can/rockchip/rockchip_canfd-core.c
> index 7107a37da36c..c3fb3176ce42 100644
> --- a/drivers/net/can/rockchip/rockchip_canfd-core.c
> +++ b/drivers/net/can/rockchip/rockchip_canfd-core.c
> @@ -937,8 +937,8 @@ static void rkcanfd_remove(struct platform_device *pdev)
>  	struct rkcanfd_priv *priv = platform_get_drvdata(pdev);
>  	struct net_device *ndev = priv->ndev;
>  
> -	can_rx_offload_del(&priv->offload);
>  	rkcanfd_unregister(priv);
> +	can_rx_offload_del(&priv->offload);
>  	free_candev(ndev);
>  }
>  


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[PATCH 3/3] can: mcan: m_can_class_unregister: fix order of unregistration calls

[Marc Kleine-Budde]

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.

The removal of the module causes the a warning, 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: 1be37d3b0414 ("can: m_can: fix periph RX path: use rx-offload to ensure skbs are sent from softirq context")
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
 drivers/net/can/m_can/m_can.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 884a6352c42b..7c430eaff5dd 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -2462,9 +2462,9 @@ EXPORT_SYMBOL_GPL(m_can_class_register);
 
 void m_can_class_unregister(struct m_can_classdev *cdev)
 {
+	unregister_candev(cdev->net);
 	if (cdev->is_peripheral)
 		can_rx_offload_del(&cdev->offload);
-	unregister_candev(cdev->net);
 }
 EXPORT_SYMBOL_GPL(m_can_class_unregister);
 

-- 
2.47.2

Re: [PATCH 3/3] can: mcan: m_can_class_unregister: fix order of unregistration calls

[Markus Schneider-Pargmann]

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On Fri May 2, 2025 at 4:13 PM CEST, Marc Kleine-Budde wrote:
> 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.
>
> The removal of the module causes the a warning, 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: 1be37d3b0414 ("can: m_can: fix periph RX path: use rx-offload to ensure skbs are sent from softirq context")
> Cc: stable@vger.kernel.org
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Reviewed-by: Markus Schneider-Pargmann <msp@baylibre.com>

> ---
>  drivers/net/can/m_can/m_can.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 884a6352c42b..7c430eaff5dd 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -2462,9 +2462,9 @@ EXPORT_SYMBOL_GPL(m_can_class_register);
>  
>  void m_can_class_unregister(struct m_can_classdev *cdev)
>  {
> +	unregister_candev(cdev->net);
>  	if (cdev->is_peripheral)
>  		can_rx_offload_del(&cdev->offload);
> -	unregister_candev(cdev->net);
>  }
>  EXPORT_SYMBOL_GPL(m_can_class_unregister);
>  


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