[GitHub] [incubator-nuttx] acassis commented on a change in pull request #5432: sched/wdog: fix delay calculation in wd_start()

[GitBox <gi...@apache.org>]

acassis commented on a change in pull request #5432:
URL: https://github.com/apache/incubator-nuttx/pull/5432#discussion_r800599616



##########
File path: sched/wdog/wd_start.c
##########
@@ -204,15 +214,31 @@ int wd_start(FAR struct wdog_s *wdog, sclock_t delay,
   up_getpicbase(&wdog->picbase);
   wdog->arg = arg;
 
-  /* Calculate delay+1, forcing the delay into a range that we can handle */
+  /* Delay for at least one tick should be performed */
 
-  if (delay <= 0)
+  if (delay == 0)
     {
       delay = 1;
     }
-  else if (++delay <= 0)
+  else
     {
-      delay--;
+      /* Calculate delay+1, forcing the delay into a range that we can
+       * handle.  In general wd_start() can be called at any time and we do
+       * not know is it at the beginning in the middle or at the end of a
+       * system clock phase, so we need to add 1 tick to ensure that the
+       * operation will be delayed for at least delay number of ticks.  But
+       * in a special case when wd_start() is called from a wd expiration
+       * callback that is called from a system tick interrupt handler we know
+       * that we are exactly at the beginning of a new phase so we do not
+       * need to add an extra tick in this case.
+       */
+
+      delay += g_wdexpiration_context ? 0 : 1;

Review comment:
       @pkarashchenko enabling it be default will bring benefits or drawbacks? I think we need to reduce the number of complex configurations inside NuttX, not create more configurations. The menu configuration "entropy" is becoming higher and higher...




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