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

commit 4ead534fba42fc4fd41163297528d2aa731cd121 upstream.

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/8732ef5f809c47c28a7be47c938b28d4@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index c0e738e..842c1db 100644 (file)
--- a/include/linux/minmax.h
+++ b/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 >