kernel.h: add {min,max}3 macros

Introduce two additional min/max macros to compare three operands.  This
will save some cycles as well as some bytes on the stack and last but not
least more pleasing as macro nesting.

[akpm@linux-foundation.org: fix warnings]
Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: Joe Perches <joe@perches.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Roland Dreier <rolandd@cisco.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index edef168a0406..8e786a27cfe6 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -651,6 +651,24 @@ static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
         (void) (&_max1 == &_max2);              \
         _max1 > _max2 ? _max1 : _max2; })
 
+#define min3(x, y, z) ({                        \
+        typeof(x) _min1 = (x);                  \
+        typeof(y) _min2 = (y);                  \
+        typeof(z) _min3 = (z);                  \
+        (void) (&_min1 == &_min2);              \
+        (void) (&_min1 == &_min3);              \
+        _min1 < _min2 ? (_min1 < _min3 ? _min1 : _min3) : \
+                (_min2 < _min3 ? _min2 : _min3); })
+
+#define max3(x, y, z) ({                        \
+        typeof(x) _max1 = (x);                  \
+        typeof(y) _max2 = (y);                  \
+        typeof(z) _max3 = (z);                  \
+        (void) (&_max1 == &_max2);              \
+        (void) (&_max1 == &_max3);              \
+        _max1 > _max2 ? (_max1 > _max3 ? _max1 : _max3) : \
+                (_max2 > _max3 ? _max2 : _max3); })
+
 /**
  * min_not_zero - return the minimum that is _not_ zero, unless both are zero
  * @x: value1