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 #define _GNU_SOURCE
  19 #undef NDEBUG
  20 #include <assert.h>
  21 #include <unistd.h>
  22 #include <sys/syscall.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25
  26 #include <stdint.h>
  27 #include <sys/types.h>
  28 #include <sys/stat.h>
  29 #include <fcntl.h>
  30
  31 #include "proc-uptime.h"
  32
  33 static inline int sys_sched_getaffinity(pid_t pid, unsigned int len, unsigned long *m)
  34 {
  35         return syscall(SYS_sched_getaffinity, pid, len, m);
  36 }
  37
  38 static inline int sys_sched_setaffinity(pid_t pid, unsigned int len, unsigned long *m)
  39 {
  40         return syscall(SYS_sched_setaffinity, pid, len, m);
  41 }
  42
  43 int main(void)
  44 {
  45         unsigned int len;
  46         unsigned long *m;
  47         unsigned int cpu;
  48         uint64_t u0, u1, i0, i1;
  49         int fd;
  50
  51         /* find out "nr_cpu_ids" */
  52         m = NULL;
  53         len = 0;
  54         do {
  55                 len += sizeof(unsigned long);
  56                 free(m);
  57                 m = malloc(len);
  58         } while (sys_sched_getaffinity(0, len, m) == -EINVAL);
  59
  60         fd = open("/proc/uptime", O_RDONLY);
  61         assert(fd >= 0);
  62
  63         proc_uptime(fd, &u0, &i0);
  64         for (cpu = 0; cpu < len * 8; cpu++) {
  65                 memset(m, 0, len);
  66                 m[cpu / (8 * sizeof(unsigned long))] |= 1UL << (cpu % (8 * sizeof(unsigned long)));
  67
  68                 /* CPU might not exist, ignore error */
  69                 sys_sched_setaffinity(0, len, m);
  70
  71                 proc_uptime(fd, &u1, &i1);
  72                 assert(u1 >= u0);
  73                 assert(i1 >= i0);
  74                 u0 = u1;
  75                 i0 = i1;
  76         }
  77
  78         return 0;
  79 }