tracing: Separate open function from set_event and available_events

The open function used by available_events is the same as set_event even
though it uses different seq functions. This causes a side effect of
writing into available_events clearing all events, even though
available_events is suppose to be read only.

There's no reason to keep a single function for just the open and have
both use different functions for everything else. It is a little
confusing and causes strange behavior. Just have each have their own
function.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 27 insertions, 19 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index dec47e70e254..cb2df3b70f7f 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -491,19 +491,6 @@ static void t_stop(struct seq_file *m, void *p)
         mutex_unlock(&event_mutex);
 }
 
-static int
-ftrace_event_seq_open(struct inode *inode, struct file *file)
-{
-        const struct seq_operations *seq_ops;
-
-        if ((file->f_mode & FMODE_WRITE) &&
-            (file->f_flags & O_TRUNC))
-                ftrace_clear_events();
-
-        seq_ops = inode->i_private;
-        return seq_open(file, seq_ops);
-}
-
 static ssize_t
 event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
                   loff_t *ppos)
@@ -980,6 +967,9 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
         return r;
 }
 
+static int ftrace_event_avail_open(struct inode *inode, struct file *file);
+static int ftrace_event_set_open(struct inode *inode, struct file *file);
+
 static const struct seq_operations show_event_seq_ops = {
         .start = t_start,
         .next = t_next,
@@ -995,14 +985,14 @@ static const struct seq_operations show_set_event_seq_ops = {
 };
 
 static const struct file_operations ftrace_avail_fops = {
-        .open = ftrace_event_seq_open,
+        .open = ftrace_event_avail_open,
         .read = seq_read,
         .llseek = seq_lseek,
         .release = seq_release,
 };
 
 static const struct file_operations ftrace_set_event_fops = {
-        .open = ftrace_event_seq_open,
+        .open = ftrace_event_set_open,
         .read = seq_read,
         .write = ftrace_event_write,
         .llseek = seq_lseek,
@@ -1078,6 +1068,26 @@ static struct dentry *event_trace_events_dir(void)
         return d_events;
 }
 
+static int
+ftrace_event_avail_open(struct inode *inode, struct file *file)
+{
+        const struct seq_operations *seq_ops = &show_event_seq_ops;
+
+        return seq_open(file, seq_ops);
+}
+
+static int
+ftrace_event_set_open(struct inode *inode, struct file *file)
+{
+        const struct seq_operations *seq_ops = &show_set_event_seq_ops;
+
+        if ((file->f_mode & FMODE_WRITE) &&
+            (file->f_flags & O_TRUNC))
+                ftrace_clear_events();
+
+        return seq_open(file, seq_ops);
+}
+
 static struct dentry *
 event_subsystem_dir(const char *name, struct dentry *d_events)
 {
@@ -1508,15 +1518,13 @@ static __init int event_trace_init(void)
                 return 0;
 
         entry = debugfs_create_file("available_events", 0444, d_tracer,
-                                    (void *)&show_event_seq_ops,
-                                    &ftrace_avail_fops);
+                                    NULL, &ftrace_avail_fops);
         if (!entry)
                 pr_warning("Could not create debugfs "
                            "'available_events' entry\n");
 
         entry = debugfs_create_file("set_event", 0644, d_tracer,
-                                    (void *)&show_set_event_seq_ops,
-                                    &ftrace_set_event_fops);
+                                    NULL, &ftrace_set_event_fops);
         if (!entry)
                 pr_warning("Could not create debugfs "
                            "'set_event' entry\n");