LINUXÄÚºËÖÐminºÍmaxºêµÄѧϰ

add linux kernel min, max define:
include/linux/kernel.h
/*
 * min()/max() macros that also do
 * strict type-checking.. See the
 * "unnecessary" pointer comparison.
 */
#define min(x,y) \
(__extension__\
({ \
        typeof(x) _x = (x);     \
        typeof(y) _y = (y);     \
        (void) (&_x == &_y);            \
        _x < _y ? _x : _y; })     \
)
#define max(x,y) \
(__extension__\
({ \
        typeof(x) _x = (x);     \
        typeof(y) _y = (y);     \
        (void) (&_x == &_y);            \
        _x > _y ? _x : _y; })     \
)
 
 
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