diff options
| author | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2021-10-13 15:37:10 +0200 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2021-10-14 14:32:19 +0200 |
| commit | 16a8e2fbb2d49111004efc1c7342e083eafabeb0 (patch) | |
| tree | ec9c22b3f88095ffa7e4885b9dfa7ba5ced1ab06 | |
| parent | spi: Fix deadlock when adding SPI controllers on SPI buses (diff) | |
| download | linux-16a8e2fbb2d49111004efc1c7342e083eafabeb0.tar.xz linux-16a8e2fbb2d49111004efc1c7342e083eafabeb0.zip | |
spi-mux: Fix false-positive lockdep splats
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>
| -rw-r--r-- | drivers/spi/spi-mux.c | 7 | ||||
| -rw-r--r-- | drivers/spi/spi.c | 12 |
2 files changed, 13 insertions, 6 deletions
diff --git a/drivers/spi/spi-mux.c b/drivers/spi/spi-mux.c index 9708b7827ff7..f5d32ec4634e 100644 --- a/drivers/spi/spi-mux.c +++ b/drivers/spi/spi-mux.c @@ -137,6 +137,13 @@ static int spi_mux_probe(struct spi_device *spi) priv = spi_controller_get_devdata(ctlr); priv->spi = spi; + /* + * Increase lockdep class as these lock are taken while the parent bus + * already holds their instance's lock. + */ + lockdep_set_subclass(&ctlr->io_mutex, 1); + lockdep_set_subclass(&ctlr->add_lock, 1); + priv->mux = devm_mux_control_get(&spi->dev, NULL); if (IS_ERR(priv->mux)) { ret = dev_err_probe(&spi->dev, PTR_ERR(priv->mux), diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 412a10586233..926b68aa45d3 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -2547,6 +2547,12 @@ struct spi_controller *__spi_alloc_controller(struct device *dev, return NULL; device_initialize(&ctlr->dev); + INIT_LIST_HEAD(&ctlr->queue); + spin_lock_init(&ctlr->queue_lock); + spin_lock_init(&ctlr->bus_lock_spinlock); + mutex_init(&ctlr->bus_lock_mutex); + mutex_init(&ctlr->io_mutex); + mutex_init(&ctlr->add_lock); ctlr->bus_num = -1; ctlr->num_chipselect = 1; ctlr->slave = slave; @@ -2819,12 +2825,6 @@ int spi_register_controller(struct spi_controller *ctlr) return id; ctlr->bus_num = id; } - INIT_LIST_HEAD(&ctlr->queue); - spin_lock_init(&ctlr->queue_lock); - spin_lock_init(&ctlr->bus_lock_spinlock); - mutex_init(&ctlr->bus_lock_mutex); - mutex_init(&ctlr->io_mutex); - mutex_init(&ctlr->add_lock); ctlr->bus_lock_flag = 0; init_completion(&ctlr->xfer_completion); if (!ctlr->max_dma_len) |