The rasdaemon service may fail to be started for the first time.

The rasdaemon creates a separate instance virtual directory on first startup, like `/sys/kernel/debug/tracing/instances/rasdaemon`.

After the directory is created, the kernel generates virtual files such as'trace_clock' and'set_event' in /sys/kernel/debug/tracing/instances/rasdaemon`.

The kernel generates virtual files and the rasdaemon accesses the virtual files at the same time. Therefore, the kernel may not generate the virtual files when the rasdaemon accesses the virtual files.

So add a 100 ms delay to give the kernel enough time to generate the files.

ras-events.c

@@ -102,15 +102,39 @@ static int get_debugfs_dir(char *tracing_dir, size_t len)
 	return ENOENT;
 }
 
+static int wait_access(char *path, int ms)
+{
+	int i;
+	for (i = 0; i < ms; i++) {
+		if (access(path, F_OK) == 0)
+			return 0;
+		usleep(1000);
+	}
+
+	log(ALL, LOG_WARNING, "wait_access() failed, %s not created in %d ms\n", path, ms);
+	return -1;
+}
+
 static int open_trace(struct ras_events *ras, char *name, int flags)
 {
+	int ret = 0;
 	char fname[MAX_PATH + 1];
 
 	strcpy(fname, ras->tracing);
 	strcat(fname, "/");
 	strcat(fname, name);
 
-	return open(fname, flags);
+	ret = wait_access(fname, 100);
+	if (ret != 0) {
+		/* use -1 to keep same error value with open() */
+		return -1;
+	}
+
+	ret = open(fname, flags);
+	if (ret == -1)
+		log(ALL, LOG_WARNING, "open_trace()->open() failed, fname=%s ret=%d errno=%d\n", fname, ret, errno);
+
+	return ret;
 }
 
 static int get_tracing_dir(struct ras_events *ras)