Bluetooth: controller: Fix ticker job_guard

Move the ticker job_guard reset to after
ticker_job_compare_update, so that the ticks_current and
ticks_slot_previous are updated before ticker_worker gets
to execute. Without this fix, there is a possibility that
ticker_worker will use incorrect ticks_slot_previous and
ticks_current value under race conditions.

Signed-off-by: Vinayak Kariappa Chettimada <[email protected]>

Author: cvinayak

subsys/bluetooth/controller/ticker/ticker.c

@@ -2364,14 +2364,14 @@ void ticker_job(void *param)
 		ticker_job_list_inquire(instance);
 	}
 
-	/* Permit worker job to run */
-	instance->job_guard = 0U;
-
 	/* update compare if head changed */
 	if (flag_compare_update) {
 		ticker_job_compare_update(instance, ticker_id_old_head);
 	}
 
+	/* Permit worker to run */
+	instance->job_guard = 0U;
+
 	/* trigger worker if deferred */
 	if (instance->worker_trigger) {
 		instance->sched_cb(TICKER_CALL_ID_JOB, TICKER_CALL_ID_WORKER, 1,