On 11.08.2025 23:06:11, Stefan Mätje wrote:

The USB stack calls during disconnect the esd_usb_disconnect() callback.
esd_usb_disconnect() calls netdev_unregister() for each network which
in turn calls the net_device_ops::ndo_stop callback esd_usb_close() if
the net device is up.

The esd_usb_close() callback tries to disable all CAN Ids and to reset
the CAN controller of the device sending appropriate control messages.

Sending these messages in .disconnect() is moot and always fails because
either the device is gone or the USB communication is already torn down
by the USB stack in the course of a rmmod operation.

This patch moves the code that sends these control messages to a new
function esd_usb_stop() which is approximately the counterpart of
esd_usb_start() to make code structure less convoluted.

It then changes esd_usb_close() not to send the control messages at
all if the ndo_stop() callback is executed from the USB .disconnect()
callback. A new flag in_usb_disconnect is added to the struct esd_usb
device structure to mark this condition which is checked by
esd_usb_close() whether to skip the send operations in esd_usb_start().

I cannot find the reference anymore, but I remember that Greg said, that
USB devices should just be quiet when being unplugged. I removed the
error prints from the gs_usb's close function, see: 5c6c313acdfc ("can:
gs_usb: gs_can_close(): don't complain about failed device reset during
ndo_stop")

regards,
Marc

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