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| /linux/drivers/tty/serial/ |
| H A D | serial_core.c | diff e21de1455a721a0cb4217b18589ede846f5b0686 Thu May 09 16:15:49 CEST 2024 Hans de Goede <hdegoede@redhat.com> serial: Clear UPF_DEAD before calling tty_port_register_device_attr_serdev()
If a serdev_device_driver is already loaded for a serdev_tty_port when it
gets registered by tty_port_register_device_attr_serdev() then that
driver's probe() method will be called immediately.
The serdev_device_driver's probe() method should then be able to call
serdev_device_open() successfully, but because UPF_DEAD is still dead
serdev_device_open() will fail with -ENXIO in this scenario:
serdev_device_open()
ctrl->ops->open() /* this callback being ttyport_open() */
tty->ops->open() /* this callback being uart_open() */
tty_port_open()
port->ops->activate() /* this callback being uart_port_activate() */
Find bit UPF_DEAD is set in uport->flags and fail with errno -ENXIO.
Fix this be clearing UPF_DEAD before tty_port_register_device_attr_serdev()
note this only moves up the UPD_DEAD clearing a small bit, before:
tty_port_register_device_attr_serdev();
mutex_unlock(&tty_port.mutex);
uart_port.flags &= ~UPF_DEAD;
mutex_unlock(&port_mutex);
after:
uart_port.flags &= ~UPF_DEAD;
tty_port_register_device_attr_serdev();
mutex_unlock(&tty_port.mutex);
mutex_unlock(&port_mutex);
Reported-by: Weifeng Liu <weifeng.liu.z@gmail.com>
Closes: https://lore.kernel.org/platform-driver-x86/20240505130800.2546640-1-weifeng.liu.z@gmail.com/
Tested-by: Weifeng Liu <weifeng.liu.z@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20240509141549.63704-1-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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