tracing: Use direct field, type and system names

The names used to display the field and type in the event format
files are copied, as well as the system name that is displayed.

All these names are created by constant values passed in.
If one of theses values were to be removed by a module, the module
would also be required to remove any event it created.

By using the strings directly, we can save over 100K of memory.

Signed-off-by: Steven Rostedt <[e-mail]>

kernel/trace/trace.h

···
 
 struct ftrace_event_field {
 	struct list_head	link;
-	char			*name;
-	char			*type;
+	const char		*name;
+	const char		*type;
 	int			filter_type;
 	int			offset;
 	int			size;

kernel/trace/trace_events.c

···
 	if (!field)
 		goto err;
 
-	field->name = kstrdup(name, GFP_KERNEL);
-	if (!field->name)
-		goto err;
-
-	field->type = kstrdup(type, GFP_KERNEL);
-	if (!field->type)
-		goto err;
+	field->name = name;
+	field->type = type;
 
 	if (filter_type == FILTER_OTHER)
 		field->filter_type = filter_assign_type(type);
···
 	return 0;
 
 err:
-	if (field)
-		kfree(field->name);
 	kmem_cache_free(field_cachep, field);
 
 	return -ENOMEM;
···
 	head = trace_get_fields(call);
 	list_for_each_entry_safe(field, next, head, link) {
 		list_del(&field->link);
-		kfree(field->type);
-		kfree(field->name);
 		kmem_cache_free(field_cachep, field);
 	}
 }
···
 		kfree(filter->filter_string);
 		kfree(filter);
 	}
-	kfree(system->name);
 	kfree(system);
 }
 
···
 		return NULL;
 
 	system->ref_count = 1;
-	system->name = kstrdup(name, GFP_KERNEL);
-
-	if (!system->name)
-		goto out_free;
+	system->name = name;
 
 	system->filter = NULL;
 
···
 	return system;
 
  out_free:
-	kfree(system->name);
 	kfree(system);
 	return NULL;
 }