minmax: allow comparisons of 'int' against 'unsigned char/short'

Since 'unsigned char/short' get promoted to 'signed int' it is safe to
compare them against an 'int' value.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Laight <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Jason A. Donenfeld <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: david-laight

include/linux/minmax.h

@@ -26,8 +26,9 @@
 	__builtin_choose_expr(__is_constexpr(is_signed_type(typeof(x))),	\
 		is_signed_type(typeof(x)), 0)
 
-#define __types_ok(x, y) \
-	(__is_signed(x) == __is_signed(y))
+#define __types_ok(x, y) 			\
+	(__is_signed(x) == __is_signed(y) ||	\
+		__is_signed((x) + 0) == __is_signed((y) + 0))
 
 #define __cmp_op_min <
 #define __cmp_op_max >