LXR linux/tools/testing/selftests/proc/proc-uptime-002.c

   1/*
   2 * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
   3 *
   4 * Permission to use, copy, modify, and distribute this software for any
   5 * purpose with or without fee is hereby granted, provided that the above
   6 * copyright notice and this permission notice appear in all copies.
   7 *
   8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15 */
  16// Test that values in /proc/uptime increment monotonically
  17// while shifting across CPUs.
  18#undef NDEBUG
  19#include <assert.h>
  20#include <unistd.h>
  21#include <sys/syscall.h>
  22#include <stdlib.h>
  23#include <string.h>
  24
  25#include <stdint.h>
  26#include <sys/types.h>
  27#include <sys/stat.h>
  28#include <fcntl.h>
  29
  30#include "proc-uptime.h"
  31
  32static inline int sys_sched_getaffinity(pid_t pid, unsigned int len, unsigned long *m)
  33{
  34        return syscall(SYS_sched_getaffinity, pid, len, m);
  35}
  36
  37static inline int sys_sched_setaffinity(pid_t pid, unsigned int len, unsigned long *m)
  38{
  39        return syscall(SYS_sched_setaffinity, pid, len, m);
  40}
  41
  42int main(void)
  43{
  44        unsigned int len;
  45        unsigned long *m;
  46        unsigned int cpu;
  47        uint64_t u0, u1, i0, i1;
  48        int fd;
  49
  50        /* find out "nr_cpu_ids" */
  51        m = NULL;
  52        len = 0;
  53        do {
  54                len += sizeof(unsigned long);
  55                free(m);
  56                m = malloc(len);
  57        } while (sys_sched_getaffinity(0, len, m) == -EINVAL);
  58
  59        fd = open("/proc/uptime", O_RDONLY);
  60        assert(fd >= 0);
  61
  62        proc_uptime(fd, &u0, &i0);
  63        for (cpu = 0; cpu < len * 8; cpu++) {
  64                memset(m, 0, len);
  65                m[cpu / (8 * sizeof(unsigned long))] |= 1UL << (cpu % (8 * sizeof(unsigned long)));
  66
  67                /* CPU might not exist, ignore error */
  68                sys_sched_setaffinity(0, len, m);
  69
  70                proc_uptime(fd, &u1, &i1);
  71                assert(u1 >= u0);
  72                assert(i1 >= i0);
  73                u0 = u1;
  74                i0 = i1;
  75        }
  76
  77        return 0;
  78}
  79