1 files changed, 88 insertions, 7 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index b92081588088..be4d3a437c17 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);