kernel_event_logger: Ignore events before subsystem init

Thread and interrupt events may well arrive before the subsystem
initialization call has been made.  Just swallow such events.

In particular, an incoming change to the way _ready_thread works
causes the main and idle thread initialization to throw thread ready
events (which isn't wrong!), which the current setup can't handle.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>

Author: Andy Ross

subsys/logging/kernel_event_logger.c

@@ -33,6 +33,8 @@ u32_t _sys_k_event_logger_sleep_start_time;
 int _sys_k_event_logger_mask;
 #endif
 
+static int initialized;
+
 /**
  * @brief Initialize the kernel event logger system.
  *
@@ -47,6 +49,8 @@ static int _sys_k_event_logger_init(struct device *arg)
 	sys_event_logger_init(&sys_k_event_logger, _sys_k_event_logger_buffer,
 		CONFIG_KERNEL_EVENT_LOGGER_BUFFER_SIZE);
 
+	initialized = 1;
+
 	return 0;
 }
 SYS_INIT(_sys_k_event_logger_init,
@@ -143,6 +147,10 @@ void _sys_k_event_logger_interrupt(void)
 {
 	u32_t data[2];
 
+	if (!initialized) {
+		return;
+	}
+
 	if (!sys_k_must_log_event(KERNEL_EVENT_LOGGER_INTERRUPT_EVENT_ID)) {
 		return;
 	}
@@ -205,6 +213,10 @@ static void log_thread_event(enum sys_k_event_logger_thread_event event,
 {
 	u32_t data[3];
 
+	if (!initialized) {
+		return;
+	}
+
 	if (!sys_k_must_log_event(KERNEL_EVENT_LOGGER_THREAD_EVENT_ID)) {
 		return;
 	}