[PATCH v2 1/2] minmax: Add in_range_inclusive() for inclusive range checks

[Guru Das Srinagesh]

in_range(val, start, len) takes a start and a length, i.e. a half-open
range. Callers that instead have an inclusive [start, end] bound have
no ready helper to reach for and either hand-roll the comparison or
convert it to in_range()'s (start, len) form themselves.

Add in_range_inclusive(val, start, end) as a direct comparison rather
than a wrapper around in_range(): computing len as end - start + 1 and
forwarding it to in_range() subverts in_range()'s 32-bit/64-bit dispatch
for sub-32-bit types via integer promotion, and overflows to 0 when @end
is the type's maximum value, silently rejecting every input instead of
accepting all of them.

val, start and end are each assigned to a __UNIQUE_ID()-generated
temporary before use, matching the __cmp_once()/__cmp_once_unique()
pattern: each argument is evaluated exactly once, and the temporary
can't be shadowed by a caller's own same-named local variable.

Assisted-by: Claude-Code:claude-sonnet-5
Signed-off-by: Guru Das Srinagesh <linux@xxxxxxxxxxx>
---
 include/linux/minmax.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index a0158db54a04..cb042733f253 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -299,6 +299,25 @@ static inline bool in_range32(u32 val, u32 start, u32 len)
 	((sizeof(start) | sizeof(len) | sizeof(val)) <= sizeof(u32) ?	\
 		in_range32(val, start, len) : in_range64(val, start, len))
 
+#define __in_range_inclusive(val, start, end, uval, ustart, uend) ({	\
+	typeof(val) uval = (val);					\
+	typeof(start) ustart = (start);					\
+	typeof(end) uend = (end);					\
+	uval >= ustart && uval <= uend;					\
+})
+
+/**
+ * in_range_inclusive - Determine if a value lies within an inclusive range.
+ * @val: Value to test.
+ * @start: First value in range.
+ * @end: Last value in range.
+ *
+ * @val, @start and @end are each evaluated exactly once.
+ */
+#define in_range_inclusive(val, start, end)				\
+	__in_range_inclusive(val, start, end, __UNIQUE_ID(val_),	\
+			     __UNIQUE_ID(start_), __UNIQUE_ID(end_))
+
 /**
  * swap - swap values of @a and @b
  * @a: first value

-- 
2.55.0