| Message ID | 20250210-gpio-set-array-helper-v3-10-d6a673674da8@baylibre.com |
|---|---|
| State | New |
| Headers | show |
| Series | gpiolib: add gpiod_multi_set_value_cansleep | expand |
On 2/10/25 4:33 PM, David Lechner wrote: > Replace bitmap array access with bitmap_write. > > Accessing the bitmap array directly is not recommended and now there is > a helper function that can be used. > > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > Signed-off-by: David Lechner <dlechner@baylibre.com> > --- > drivers/iio/resolver/ad2s1210.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/resolver/ad2s1210.c b/drivers/iio/resolver/ad2s1210.c > index 7f18df790157f1e411fb70de193a49f0677c999f..04879e6d538bce664469c5f6759d8b1cedea16e9 100644 > --- a/drivers/iio/resolver/ad2s1210.c > +++ b/drivers/iio/resolver/ad2s1210.c > @@ -46,6 +46,7 @@ > */ > > #include <linux/bitfield.h> > +#include <linux/bitmap.h> > #include <linux/bits.h> > #include <linux/cleanup.h> > #include <linux/clk.h> > @@ -180,7 +181,7 @@ static int ad2s1210_set_mode(struct ad2s1210_state *st, enum ad2s1210_mode mode) > if (!gpios) > return mode == st->fixed_mode ? 0 : -EOPNOTSUPP; > > - bitmap[0] = mode; > + bitmap_write(bitmap, mode, 0, 2); > > return gpiod_multi_set_value_cansleep(gpios, bitmap); > } > @@ -1470,7 +1471,7 @@ static int ad2s1210_setup_gpios(struct ad2s1210_state *st) > return dev_err_probe(dev, -EINVAL, > "requires exactly 2 resolution-gpios\n"); > > - bitmap[0] = st->resolution; > + bitmap_write(bitmap, st->resolution, 0, 2); > > ret = gpiod_multi_set_value_cansleep(resolution_gpios, bitmap); > if (ret < 0) > There is actually a bug here pointed out in a similar patch. bitmap_write() only modifies the bitmap, so this introduces an unintialized use bug. [1] Here, we only use the bits that we set, so runtime behavior would not actually be buggy but still best to fully initialize the memory. I'm a bit surprised that my local compiler and iio/testing both didn't catch that since GCC 14 caught it in the other driver. [1]: https://lore.kernel.org/linux-gpio/20250217132152.29d86d6c@jic23-huawei/T/#m3163d2c5db5b7376504d8ad6f23716f1119de761 The fix is simple, we can zero-initialize the bitmap. diff --git a/drivers/iio/resolver/ad2s1210.c b/drivers/iio/resolver/ad2s1210.c index 04879e6d538b..ab860cedecd1 100644 --- a/drivers/iio/resolver/ad2s1210.c +++ b/drivers/iio/resolver/ad2s1210.c @@ -176,7 +176,7 @@ struct ad2s1210_state { static int ad2s1210_set_mode(struct ad2s1210_state *st, enum ad2s1210_mode mode) { struct gpio_descs *gpios = st->mode_gpios; - DECLARE_BITMAP(bitmap, 2); + DECLARE_BITMAP(bitmap, 2) = { }; if (!gpios) return mode == st->fixed_mode ? 0 : -EOPNOTSUPP; @@ -1427,7 +1427,7 @@ static int ad2s1210_setup_gpios(struct ad2s1210_state *st) struct device *dev = &st->sdev->dev; struct gpio_descs *resolution_gpios; struct gpio_desc *reset_gpio; - DECLARE_BITMAP(bitmap, 2); + DECLARE_BITMAP(bitmap, 2) = { }; int ret; /* should not be sampling on startup */
diff --git a/drivers/iio/resolver/ad2s1210.c b/drivers/iio/resolver/ad2s1210.c index 7f18df790157f1e411fb70de193a49f0677c999f..04879e6d538bce664469c5f6759d8b1cedea16e9 100644 --- a/drivers/iio/resolver/ad2s1210.c +++ b/drivers/iio/resolver/ad2s1210.c @@ -46,6 +46,7 @@ */ #include <linux/bitfield.h> +#include <linux/bitmap.h> #include <linux/bits.h> #include <linux/cleanup.h> #include <linux/clk.h> @@ -180,7 +181,7 @@ static int ad2s1210_set_mode(struct ad2s1210_state *st, enum ad2s1210_mode mode) if (!gpios) return mode == st->fixed_mode ? 0 : -EOPNOTSUPP; - bitmap[0] = mode; + bitmap_write(bitmap, mode, 0, 2); return gpiod_multi_set_value_cansleep(gpios, bitmap); } @@ -1470,7 +1471,7 @@ static int ad2s1210_setup_gpios(struct ad2s1210_state *st) return dev_err_probe(dev, -EINVAL, "requires exactly 2 resolution-gpios\n"); - bitmap[0] = st->resolution; + bitmap_write(bitmap, st->resolution, 0, 2); ret = gpiod_multi_set_value_cansleep(resolution_gpios, bitmap); if (ret < 0)