fixup! ztimer: acquire and release clock for running timers

jue89 · jue89 · commit ba77e7b3fc8e · 2022-02-04T15:44:25.000+01:00
diff --git a/sys/ztimer/core.c b/sys/ztimer/core.c
@@ -138,17 +138,9 @@ uint32_t ztimer_set(ztimer_clock_t *clock, ztimer_t *timer, uint32_t val)
 
     unsigned state = irq_disable();
 
-    uint32_t now = _ztimer_update_head_offset(clock);
-
-    bool was_set = false;
-    if (_is_set(clock, timer)) {
-        was_set = _del_entry_from_list(clock, &timer->base);
-    }
-
 #if MODULE_ZTIMER_ONDEMAND
-    /* if the timer wasn't reset on this clock, it acquires the required
-     * ztimer_clock_t. */
-    if (!was_set && _ztimer_acquire(clock) == true) {
+    /* warm up our clock ... */
+    if (_ztimer_acquire(clock) == true) {
         /* compensate delay that turning on the clock has introduced */
         if (val > clock->adjust_clock_start) {
             val -= clock->adjust_clock_start;
@@ -159,6 +151,13 @@ uint32_t ztimer_set(ztimer_clock_t *clock, ztimer_t *timer, uint32_t val)
     }
 #endif
 
+    uint32_t now = _ztimer_update_head_offset(clock);
+
+    bool was_set = false;
+    if (_is_set(clock, timer)) {
+        was_set = _del_entry_from_list(clock, &timer->base);
+    }
+
     /* optionally subtract a configurable adjustment value */
     if (val > clock->adjust_set) {
         val -= clock->adjust_set;
@@ -179,6 +178,19 @@ uint32_t ztimer_set(ztimer_clock_t *clock, ztimer_t *timer, uint32_t val)
         clock->ops->set(clock, val);
     }
 
+    /* the clock is armed now
+     * everthing down below doesn't impact timing */
+
+#if MODULE_ZTIMER_ONDEMAND
+    if (was_set) {
+        /* the given ztimer_t was set in the past
+         * remove the previously set instance */
+        _ztimer_release(clock);
+    }
+#else
+    (void)was_set;
+#endif
+
     irq_restore(state);
     return now;
 }
@@ -449,6 +461,9 @@ void ztimer_handler(ztimer_clock_t *clock)
             entry->callback(entry->arg);
 #if MODULE_ZTIMER_ONDEMAND
             no_clock_user_left = _ztimer_release(clock);
+            if (no_clock_user_left) {
+                break;
+            }
 #endif
             entry = _now_next(clock);
             if (!entry) {
