The patch titled
Subject: iio: magnetometer: yas530: use signed integer type for clamp limits
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
iio-magnetometer-yas530-use-signed-integer-type-for-clamp-limits.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/iio-magnetometer-yas530-use-signed-integer-type-for-clamp-limits.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Jakob Hauser <jahau@xxxxxxxxxxxxxx>
Subject: iio: magnetometer: yas530: use signed integer type for clamp limits
Date: Fri, 29 Nov 2024 22:25:07 +0100
In the function yas537_measure() there is a clamp_val() with limits of
-BIT(13) and BIT(13) - 1. The input clamp value h[] is of type s32. The
BIT() is of type unsigned long integer due to its define in
include/vdso/bits.h. The lower limit -BIT(13) is recognized as -8192 but
expressed as an unsigned long integer. The size of an unsigned long
integer differs between 32-bit and 64-bit architectures. Converting this
to type s32 may lead to undesired behavior.
Additionally, in the calculation lines h[0], h[1] and h[2] the unsigned
long integer divisor BIT(13) causes an unsigned division, shifting the
left-hand side of the equation back and forth, possibly ending up in large
positive values instead of negative values on 32-bit architectures.
To solve those two issues, declare a signed integer with a value of
BIT(13).
There is another omission in the clamp line: clamp_val() returns a value
and it's going nowhere here. Self-assign it to h[i] to make use of the
clamp macro.
Finally, replace clamp_val() macro by clamp() because after changing the
limits from type unsigned long integer to signed integer it's fine that
way.
Link: https://lkml.kernel.org/r/11609b2243c295d65ab4d47e78c239d61ad6be75.1732914810.git.jahau@xxxxxxxxxxxxxx
Fixes: 65f79b501030 ("iio: magnetometer: yas530: Add YAS537 variant")
Signed-off-by: Jakob Hauser <jahau@xxxxxxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202411230458.dhZwh3TT-lkp@xxxxxxxxx/
Closes: https://lore.kernel.org/oe-kbuild-all/202411282222.oF0B4110-lkp@xxxxxxxxx/
Cc: David Laight <david.laight@xxxxxxxxxx>
Cc: Jonathan Cameron <jic23@xxxxxxxxxx>
Cc: Lars-Peter Clausen <lars@xxxxxxxxxx>
Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/iio/magnetometer/yamaha-yas530.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
--- a/drivers/iio/magnetometer/yamaha-yas530.c~iio-magnetometer-yas530-use-signed-integer-type-for-clamp-limits
+++ a/drivers/iio/magnetometer/yamaha-yas530.c
@@ -372,6 +372,7 @@ static int yas537_measure(struct yas5xx
u8 data[8];
u16 xy1y2[3];
s32 h[3], s[3];
+ int half_range = BIT(13);
int i, ret;
mutex_lock(&yas5xx->lock);
@@ -406,13 +407,13 @@ static int yas537_measure(struct yas5xx
/* The second version of YAS537 needs to include calibration coefficients */
if (yas5xx->version == YAS537_VERSION_1) {
for (i = 0; i < 3; i++)
- s[i] = xy1y2[i] - BIT(13);
- h[0] = (c->k * (128 * s[0] + c->a2 * s[1] + c->a3 * s[2])) / BIT(13);
- h[1] = (c->k * (c->a4 * s[0] + c->a5 * s[1] + c->a6 * s[2])) / BIT(13);
- h[2] = (c->k * (c->a7 * s[0] + c->a8 * s[1] + c->a9 * s[2])) / BIT(13);
+ s[i] = xy1y2[i] - half_range;
+ h[0] = (c->k * (128 * s[0] + c->a2 * s[1] + c->a3 * s[2])) / half_range;
+ h[1] = (c->k * (c->a4 * s[0] + c->a5 * s[1] + c->a6 * s[2])) / half_range;
+ h[2] = (c->k * (c->a7 * s[0] + c->a8 * s[1] + c->a9 * s[2])) / half_range;
for (i = 0; i < 3; i++) {
- clamp_val(h[i], -BIT(13), BIT(13) - 1);
- xy1y2[i] = h[i] + BIT(13);
+ h[i] = clamp(h[i], -half_range, half_range - 1);
+ xy1y2[i] = h[i] + half_range;
}
}
_
Patches currently in -mm which might be from jahau@xxxxxxxxxxxxxx are
iio-magnetometer-yas530-use-signed-integer-type-for-clamp-limits.patch
