netdev - Re: [PATCH net 5/6] can: mcan: m_can_class_unregister(): fix order of unregistration calls

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Message-ID: <1a595587-f0d2-4ac1-a751-bf80e186a180@intel.com>
Date: Tue, 6 May 2025 11:29:42 -0700
From: Jacob Keller <jacob.e.keller@...el.com>
To: Marc Kleine-Budde <mkl@...gutronix.de>, <netdev@...r.kernel.org>
CC: <davem@...emloft.net>, <kuba@...nel.org>, <linux-can@...r.kernel.org>,
	<kernel@...gutronix.de>, <stable@...r.kernel.org>, Markus Schneider-Pargmann
	<msp@...libre.com>
Subject: Re: [PATCH net 5/6] can: mcan: m_can_class_unregister(): fix order of
 unregistration calls



On 5/6/2025 6:56 AM, 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 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@...r.kernel.org
> Link: https://patch.msgid.link/20250502-can-rx-offload-del-v1-3-59a9b131589d@pengutronix.de
> Reviewed-by: Markus Schneider-Pargmann <msp@...libre.com>
> Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.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 326ede9d400f..c2c116ce1087 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -2463,9 +2463,9 @@ 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);
>  


Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>