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

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Message-Id: <20250502-can-rx-offload-del-v1-0-59a9b131589d@pengutronix.de>
Date: Fri, 02 May 2025 16:13:43 +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 0/3] can: rx-offload: 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().

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@...gutronix.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@...gutronix.de>