From: Andy Shevchenko andriy.shevchenko@linux.intel.com
[ Upstream commit f60d7270c8a3d2beb1c23ae0da42497afa3584c2 ]
ffz(), that has been used to count unused native CSs, might cause undefined behaviour when called against ~0U. To fix that, open code it with ffs(~value) - 1.
Fixes: 7d93aecdb58d ("spi: Add generic support for unused native cs with cs-gpios") Signed-off-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Link: https://lore.kernel.org/r/20210420164425.40287-2-andriy.shevchenko@linux.int... Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/spi/spi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index a1a85f0baf7c..8c261eac2cee 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -2614,7 +2614,7 @@ static int spi_get_gpio_descs(struct spi_controller *ctlr) native_cs_mask |= BIT(i); }
- ctlr->unused_native_cs = ffz(native_cs_mask); + ctlr->unused_native_cs = ffs(~native_cs_mask) - 1;
if ((ctlr->flags & SPI_MASTER_GPIO_SS) && num_cs_gpios && ctlr->max_native_cs && ctlr->unused_native_cs >= ctlr->max_native_cs) {