spi: Switch to signed types for *_native_cs SPI controller fields

commit 35f3f8504c3b60a1ae5576e178b27fc0ddd6157d upstream.

While fixing undefined behaviour the commit f60d7270c8a3 ("spi: Avoid
undefined behaviour when counting unused native CSs") missed the case
when all CSs are GPIOs and thus unused_native_cs will be evaluated to
-1 in unsigned representation. This will falsely trigger a condition
in the spi_get_gpio_descs().

Switch to signed types for *_native_cs SPI controller fields to fix above.

Fixes: f60d7270c8a3 ("spi: Avoid undefined behaviour when counting unused native CSs")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210510131242.49455-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Nobuhiro Iwamatsu (CIP) <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 2d906b9c149929fb590e42dcdbc0998891bbc868..e1d88630ff24390938ad205bbb34a941e8fafb4c 100644 (file)
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -646,8 +646,8 @@ struct spi_controller {
        int                     *cs_gpios;
        struct gpio_desc        **cs_gpiods;
        bool                    use_gpio_descriptors;
-       u8                      unused_native_cs;
-       u8                      max_native_cs;
+       s8                      unused_native_cs;
+       s8                      max_native_cs;
 
        /* statistics */
        struct spi_statistics   statistics;