[PATCH] spi: take the SPI IO-mutex in the spi_set_cs_timing method

[PATCH] spi: take the SPI IO-mutex in the spi_set_cs_timing method

[Leilk Liu]

this patch takes the io_mutex to prevent an unprotected HW
register modification in the set_cs_timing callback.

Fixes: 4cea6b8cc34e ("spi: add power control when set_cs_timing")
Signed-off-by: Leilk Liu <leilk.liu@mediatek.com>
---
 drivers/spi/spi.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 2350d131871b..6bda471b9621 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -3459,9 +3459,12 @@ int spi_set_cs_timing(struct spi_device *spi, struct spi_delay *setup,
 
 	if (spi->controller->set_cs_timing &&
 	    !(spi->cs_gpiod || gpio_is_valid(spi->cs_gpio))) {
+		mutex_lock(&spi->controller->io_mutex);
+
 		if (spi->controller->auto_runtime_pm) {
 			status = pm_runtime_get_sync(parent);
 			if (status < 0) {
+				mutex_unlock(&spi->controller->io_mutex);
 				pm_runtime_put_noidle(parent);
 				dev_err(&spi->controller->dev, "Failed to power device: %d\n",
 					status);
@@ -3472,11 +3475,13 @@ int spi_set_cs_timing(struct spi_device *spi, struct spi_delay *setup,
 								hold, inactive);
 			pm_runtime_mark_last_busy(parent);
 			pm_runtime_put_autosuspend(parent);
-			return status;
 		} else {
-			return spi->controller->set_cs_timing(spi, setup, hold,
+			status = spi->controller->set_cs_timing(spi, setup, hold,
 							      inactive);
 		}
+
+		mutex_unlock(&spi->controller->io_mutex);
+		return status;
 	}
 
 	if ((setup && setup->unit == SPI_DELAY_UNIT_SCK) ||
-- 
2.18.0

Re: [PATCH] spi: take the SPI IO-mutex in the spi_set_cs_timing method

[Mark Brown]

On Sat, 8 May 2021 14:02:14 +0800, Leilk Liu wrote:
> this patch takes the io_mutex to prevent an unprotected HW
> register modification in the set_cs_timing callback.

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: take the SPI IO-mutex in the spi_set_cs_timing method
      commit: dc5fa590273890a8541ce6e999d606bfb2d73797

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark