cpumask: make cpumask_size() return "unsigned int"

CPUmasks are never big enough to warrant 64-bit code.

Space savings:

	add/remove: 0/0 grow/shrink: 1/4 up/down: 3/-17 (-14)
	Function                                     old     new   delta
	sched_init_numa                             1530    1533      +3
	compat_sys_sched_setaffinity                 160     159      -1
	sys_sched_getaffinity                        197     195      -2
	sys_sched_setaffinity                        183     176      -7
	compat_sys_sched_getaffinity                 179     172      -7

Link: http://lkml.kernel.org/r/20171204165531.GA8221@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/cpumask.h

@@ -640,7 +640,7 @@ static inline int cpulist_parse(const char *buf, struct cpumask *dstp)
 /**
  * cpumask_size - size to allocate for a 'struct cpumask' in bytes
  */
-static inline size_t cpumask_size(void)
+static inline unsigned int cpumask_size(void)
 {
 	return BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long);
 }

kernel/compat.c

@@ -355,7 +355,7 @@ COMPAT_SYSCALL_DEFINE3(sched_getaffinity, compat_pid_t,  pid, unsigned int, len,
 
 	ret = sched_getaffinity(pid, mask);
 	if (ret == 0) {
-		size_t retlen = min_t(size_t, len, cpumask_size());
+		unsigned int retlen = min(len, cpumask_size());
 
 		if (compat_put_bitmap(user_mask_ptr, cpumask_bits(mask), retlen * 8))
 			ret = -EFAULT;

kernel/sched/core.c

@@ -4853,7 +4853,7 @@ SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
 
 	ret = sched_getaffinity(pid, mask);
 	if (ret == 0) {
-		size_t retlen = min_t(size_t, len, cpumask_size());
+		unsigned int retlen = min(len, cpumask_size());
 
 		if (copy_to_user(user_mask_ptr, mask, retlen))
 			ret = -EFAULT;