1 files changed, 88 insertions, 7 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index b9208158808..be4d3a437c1 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -770,7 +770,11 @@ event_subsystem_dir(const char *name, struct dentry *d_events)
 }
 
 static int
-event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
+event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
+		 const struct file_operations *id,
+		 const struct file_operations *enable,
+		 const struct file_operations *filter,
+		 const struct file_operations *format)
 {
 	struct dentry *entry;
 	int ret;
@@ -800,11 +804,11 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
 
 	if (call->regfunc)
 		entry = trace_create_file("enable", 0644, call->dir, call,
-					  &ftrace_enable_fops);
+					  enable);
 
 	if (call->id)
 		entry = trace_create_file("id", 0444, call->dir, call,
-					  &ftrace_event_id_fops);
+					  id);
 
 	if (call->define_fields) {
 		ret = call->define_fields();
@@ -814,7 +818,7 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
 			return ret;
 		}
 		entry = trace_create_file("filter", 0644, call->dir, call,
-					  &ftrace_event_filter_fops);
+					  filter);
 	}
 
 	/* A trace may not want to export its format */
@@ -822,7 +826,7 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
 		return 0;
 
 	entry = trace_create_file("format", 0444, call->dir, call,
-				  &ftrace_event_format_fops);
+				  format);
 
 	return 0;
 }
@@ -833,8 +837,60 @@ event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
 	     event++)
 
 #ifdef CONFIG_MODULES
+
+static LIST_HEAD(ftrace_module_file_list);
+
+/*
+ * Modules must own their file_operations to keep up with
+ * reference counting.
+ */
+struct ftrace_module_file_ops {
+	struct list_head		list;
+	struct module			*mod;
+	struct file_operations		id;
+	struct file_operations		enable;
+	struct file_operations		format;
+	struct file_operations		filter;
+};
+
+static struct ftrace_module_file_ops *
+trace_create_file_ops(struct module *mod)
+{
+	struct ftrace_module_file_ops *file_ops;
+
+	/*
+	 * This is a bit of a PITA. To allow for correct reference
+	 * counting, modules must "own" their file_operations.
+	 * To do this, we allocate the file operations that will be
+	 * used in the event directory.
+	 */
+
+	file_ops = kmalloc(sizeof(*file_ops), GFP_KERNEL);
+	if (!file_ops)
+		return NULL;
+
+	file_ops->mod = mod;
+
+	file_ops->id = ftrace_event_id_fops;
+	file_ops->id.owner = mod;
+
+	file_ops->enable = ftrace_enable_fops;
+	file_ops->enable.owner = mod;
+
+	file_ops->filter = ftrace_event_filter_fops;
+	file_ops->filter.owner = mod;
+
+	file_ops->format = ftrace_event_format_fops;
+	file_ops->format.owner = mod;
+
+	list_add(&file_ops->list, &ftrace_module_file_list);
+
+	return file_ops;
+}
+
 static void trace_module_add_events(struct module *mod)
 {
+	struct ftrace_module_file_ops *file_ops = NULL;
 	struct ftrace_event_call *call, *start, *end;
 	struct dentry *d_events;
 
@@ -852,14 +908,27 @@ static void trace_module_add_events(struct module *mod)
 		/* The linker may leave blanks */
 		if (!call->name)
 			continue;
+
+		/*
+		 * This module has events, create file ops for this module
+		 * if not already done.
+		 */
+		if (!file_ops) {
+			file_ops = trace_create_file_ops(mod);
+			if (!file_ops)
+				return;
+		}
 		call->mod = mod;
 		list_add(&call->list, &ftrace_events);
-		event_create_dir(call, d_events);
+		event_create_dir(call, d_events,
+				 &file_ops->id, &file_ops->enable,
+				 &file_ops->filter, &file_ops->format);
 	}
 }
 
 static void trace_module_remove_events(struct module *mod)
 {
+	struct ftrace_module_file_ops *file_ops;
 	struct ftrace_event_call *call, *p;
 
 	list_for_each_entry_safe(call, p, &ftrace_events, list) {
@@ -874,6 +943,16 @@ static void trace_module_remove_events(struct module *mod)
 			list_del(&call->list);
 		}
 	}
+
+	/* Now free the file_operations */
+	list_for_each_entry(file_ops, &ftrace_module_file_list, list) {
+		if (file_ops->mod == mod)
+			break;
+	}
+	if (&file_ops->list != &ftrace_module_file_list) {
+		list_del(&file_ops->list);
+		kfree(file_ops);
+	}
 }
 
 static int trace_module_notify(struct notifier_block *self,
@@ -954,7 +1033,9 @@ static __init int event_trace_init(void)
 		if (!call->name)
 			continue;
 		list_add(&call->list, &ftrace_events);
-		event_create_dir(call, d_events);
+		event_create_dir(call, d_events, &ftrace_event_id_fops,
+				 &ftrace_enable_fops, &ftrace_event_filter_fops,
+				 &ftrace_event_format_fops);
 	}
 
 	ret = register_module_notifier(&trace_module_nb);