io_mutex is taken by spi_setup() and spi-mux's .setup() callback calls spi_setup() which results in a nested lock of io_mutex. add_lock is taken by spi_add_device(). The device_add() call in there can result in calling spi-mux's .probe() callback which registers its own spi controller which in turn results in spi_add_device() being called again. To fix this initialize the controller's locks already in spi_alloc_controller() to give spi_mux_probe() a chance to set the lockdep subclass. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Link: https://lore.kernel.org/r/20211013133710.2679703-2-u.kleine-koenig@pengutronix.de Signed-off-by: Mark Brown <broonie@kernel.org>