kernel/watchdog.c

   1 /*
   2  * This is arch independent NMI watchdog implementaion part. It is used to
   3  * detect kernel lockups and help debugging. each architecture must add its own
   4  * low level code that triggers periodic checks
   5  */
   6
   7 #include "watchdog.h"
   8
   9 unsigned watchdog_local_timer_ticks;
  10 struct arch_watchdog *watchdog;
  11 int watchdog_enabled;
  12
  13 void nmi_watchdog_handler(struct nmi_frame * frame)
  14 {
  15         /* FIXME this should be CPU local */
  16         static unsigned no_ticks;
  17         static unsigned last_tick_count = (unsigned) -1;
  18
  19         /*
  20          * when debugging on serial console, printing takes a lot of time some
  21          * times while the kernel is certainly not locked up. We don't want to
  22          * report a lockup in such situation
  23          */
  24         if (serial_debug_active)
  25                 goto reset_and_continue;
  26
  27         if (last_tick_count != watchdog_local_timer_ticks) {
  28                 if (no_ticks == 1) {
  29                         printf("watchdog : kernel unlocked\n");
  30                         no_ticks = 0;
  31                 }
  32                 /* we are still ticking, everything seems good */
  33                 last_tick_count = watchdog_local_timer_ticks;
  34                 goto reset_and_continue;
  35         }
  36
  37         /*
  38          * if watchdog_local_timer_ticks didn't changed since last time, give it
  39          * some more time and only if it still dead, trigger the watchdog alarm
  40          */
  41         if (++no_ticks < 10) {
  42                 if (no_ticks == 1)
  43                         printf("WARNING watchdog : possible kernel lockup\n");
  44                 goto reset_and_continue;
  45         }
  46
  47         arch_watchdog_lockup(frame);
  48
  49 reset_and_continue:
  50         if (watchdog->reinit)
  51                 watchdog->reinit(cpuid);
  52 }