2 files changed, 54 insertions, 4 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2c3cba59552d..c7fbf93f1b7c 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -226,6 +226,9 @@ extern struct list_head ftrace_trace_arrays;
 
 extern struct mutex trace_types_lock;
 
+extern int trace_array_get(struct trace_array *tr);
+extern void trace_array_put(struct trace_array *tr);
+
 /*
  * The global tracer (top) should be the first trace array added,
  * but we check the flag anyway.
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 35c6f23c71b2..920e08fb53b3 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -410,6 +410,35 @@ static void put_system(struct ftrace_subsystem_dir *dir)
 }
 
 /*
+ * Open and update trace_array ref count.
+ * Must have the current trace_array passed to it.
+ */
+static int tracing_open_generic_file(struct inode *inode, struct file *filp)
+{
+        struct ftrace_event_file *file = inode->i_private;
+        struct trace_array *tr = file->tr;
+        int ret;
+
+        if (trace_array_get(tr) < 0)
+                return -ENODEV;
+
+        ret = tracing_open_generic(inode, filp);
+        if (ret < 0)
+                trace_array_put(tr);
+        return ret;
+}
+
+static int tracing_release_generic_file(struct inode *inode, struct file *filp)
+{
+        struct ftrace_event_file *file = inode->i_private;
+        struct trace_array *tr = file->tr;
+
+        trace_array_put(tr);
+
+        return 0;
+}
+
+/*
  * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
  */
 static int __ftrace_set_clr_event(struct trace_array *tr, const char *match,
@@ -1032,9 +1061,17 @@ static int subsystem_open(struct inode *inode, struct file *filp)
         /* Some versions of gcc think dir can be uninitialized here */
         WARN_ON(!dir);
 
+        /* Still need to increment the ref count of the system */
+        if (trace_array_get(tr) < 0) {
+                put_system(dir);
+                return -ENODEV;
+        }
+
         ret = tracing_open_generic(inode, filp);
-        if (ret < 0)
+        if (ret < 0) {
+                trace_array_put(tr);
                 put_system(dir);
+        }
 
         return ret;
 }
@@ -1045,16 +1082,23 @@ static int system_tr_open(struct inode *inode, struct file *filp)
         struct trace_array *tr = inode->i_private;
         int ret;
 
+        if (trace_array_get(tr) < 0)
+                return -ENODEV;
+
         /* Make a temporary dir that has no system but points to tr */
         dir = kzalloc(sizeof(*dir), GFP_KERNEL);
-        if (!dir)
+        if (!dir) {
+                trace_array_put(tr);
                 return -ENOMEM;
+        }
 
         dir->tr = tr;
 
         ret = tracing_open_generic(inode, filp);
-        if (ret < 0)
+        if (ret < 0) {
+                trace_array_put(tr);
                 kfree(dir);
+        }
 
         filp->private_data = dir;
 
@@ -1065,6 +1109,8 @@ static int subsystem_release(struct inode *inode, struct file *file)
 {
         struct ftrace_subsystem_dir *dir = file->private_data;
 
+        trace_array_put(dir->tr);
+
         /*
          * If dir->subsystem is NULL, then this is a temporary
          * descriptor that was made for a trace_array to enable
@@ -1192,9 +1238,10 @@ static const struct file_operations ftrace_set_event_fops = {
 };
 
 static const struct file_operations ftrace_enable_fops = {
-        .open = tracing_open_generic,
+        .open = tracing_open_generic_file,
         .read = event_enable_read,
         .write = event_enable_write,
+        .release = tracing_release_generic_file,
         .llseek = default_llseek,
 };