This is a port of Linux commit 048a9883267f9b8f8e05dca9e9e8e6f991eea61e:
| Author: Alexey Dobriyan <adobri...@gmail.com>
| AuthorDate: Sat May 20 21:25:19 2023 +0300
|
| include/linux/math.h: fix mult_frac() multiple argument evaluation bug
|
| mult_frac() evaluates _all_ arguments multiple times in the body.
|
| Clarify comment while I'm at it.
|
| Link: https://lkml.kernel.org/r/f9f9fdbb-ec8e-4f5e-a998-2a58627a1a43@p183
| Signed-off-by: Alexey Dobriyan <adobri...@gmail.com>
| Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Ahmad Fatoum <a.fat...@pengutronix.de>
---
include/linux/kernel.h | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index c411ac0860dd..cd7dac73f93a 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -107,17 +107,17 @@ extern long long simple_strtoll(const char *,char
**,unsigned int);
} \
)
-/*
- * Multiplies an integer by a fraction, while avoiding unnecessary
- * overflow or loss of precision.
- */
-#define mult_frac(x, numer, denom)( \
-{ \
- typeof(x) quot = (x) / (denom); \
- typeof(x) rem = (x) % (denom); \
- (quot * (numer)) + ((rem * (numer)) / (denom)); \
-} \
-)
+/* Calculate "x * n / d" without unnecessary overflow or loss of precision. */
+#define mult_frac(x, n, d) \
+({ \
+ typeof(x) x_ = (x); \
+ typeof(n) n_ = (n); \
+ typeof(d) d_ = (d); \
+ \
+ typeof(x_) q = x_ / d_; \
+ typeof(x_) r = x_ % d_; \
+ q * n_ + r * n_ / d_; \
+})
extern const char hex_asc[];
#define hex_asc_lo(x) hex_asc[((x) & 0x0f)]
--
2.39.2
