On Thu, 20 Feb 2025 14:54:53 -0600 David Lechner <dlechner@xxxxxxxxxxxx> wrote: > 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@xxxxxxxxxx> > > Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx> > > --- > > 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. Ignore previous. I'm looking at wrong branch. I can tweak this just fine. Done so and tree pushed out. > > 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 */ >
