fs/proc/uptime.c

   1 #include <linux/init.h>
   2 #include <linux/proc_fs.h>
   3 #include <linux/sched.h>
   4 #include <linux/time.h>
   5 #include <asm/cputime.h>
   6
   7 static int proc_calc_metrics(char *page, char **start, off_t off,
   8                                  int count, int *eof, int len)
   9 {
  10         if (len <= off + count)
  11                 *eof = 1;
  12         *start = page + off;
  13         len -= off;
  14         if (len > count)
  15                 len = count;
  16         if (len < 0)
  17                 len = 0;
  18         return len;
  19 }
  20
  21 static int uptime_read_proc(char *page, char **start, off_t off, int count,
  22                             int *eof, void *data)
  23 {
  24         struct timespec uptime;
  25         struct timespec idle;
  26         int len;
  27         cputime_t idletime = cputime_add(init_task.utime, init_task.stime);
  28
  29         do_posix_clock_monotonic_gettime(&uptime);
  30         monotonic_to_bootbased(&uptime);
  31         cputime_to_timespec(idletime, &idle);
  32         len = sprintf(page, "%lu.%02lu %lu.%02lu\n",
  33                         (unsigned long) uptime.tv_sec,
  34                         (uptime.tv_nsec / (NSEC_PER_SEC / 100)),
  35                         (unsigned long) idle.tv_sec,
  36                         (idle.tv_nsec / (NSEC_PER_SEC / 100)));
  37         return proc_calc_metrics(page, start, off, count, eof, len);
  38 }
  39
  40 static int __init proc_uptime_init(void)
  41 {
  42         create_proc_read_entry("uptime", 0, NULL, uptime_read_proc, NULL);
  43         return 0;
  44 }
  45 module_init(proc_uptime_init);