linux-kernel - [PATCH] cpumask: make cpumask

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Message-ID: <20171204165531.GA8221@avx2>
Date:   Mon, 4 Dec 2017 19:55:31 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] 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

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---

 include/linux/cpumask.h |    2 +-
 kernel/compat.c         |    2 +-
 kernel/sched/core.c     |    2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

--- a/include/linux/cpumask.h
+++ b/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);
 }
--- a/kernel/compat.c
+++ b/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;
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4799,7 +4799,7 @@ 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;