patch "iio:core: fix IIO_VAL_FRACTIONAL sign handling" added to staging-linus

This is a note to let you know that I've just added the patch titled

iio:core: fix IIO_VAL_FRACTIONAL sign handling

to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From: Gregor Boirie <[email protected]>
Date: Fri, 2 Sep 2016 20:27:46 +0200
Subject: iio:core: fix IIO_VAL_FRACTIONAL sign handling

7985e7c100 ("iio: Introduce a new fractional value type") introduced a new IIO_VAL_FRACTIONAL value type meant to represent rational type numbers expressed by a numerator and denominator combination.

Formating of IIO_VAL_FRACTIONAL values relies upon do_div() usage. This fails handling negative values properly since parameters are reevaluated as unsigned values.
Fix this by using div_s64_rem() instead. Computed integer part will carry properly signed value. Formatted fractional part will always be positive.

---
 drivers/iio/industrialio-core.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

index f914d5d140e4..d2b889918c3e 100644
@@ -613,9 +613,8 @@ ssize_t iio_format_value(char *buf, unsigned int type, int size, int *vals)
 			return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
 	case IIO_VAL_FRACTIONAL:
 		tmp = div_s64((s64)vals[0] * 1000000000LL, vals[1]);
-		vals[1] = do_div(tmp, 1000000000LL);
-		vals[0] = tmp;
-		return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
+		vals[0] = (int)div_s64_rem(tmp, 1000000000, &vals[1]);
+		return sprintf(buf, "%d.%09u\n", vals[0], abs(vals[1]));
 	case IIO_VAL_FRACTIONAL_LOG2:
 		tmp = (s64)vals[0] * 1000000000LL >> vals[1];
 		vals[1] = do_div(tmp, 1000000000LL);

2.9.3