[PATCH 14/19] tracing: Separate open function from set_event and available_events

[Steven Rostedt]

From: Steven Rostedt <srost...@redhat.com>

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 <rost...@goodmis.org>
---
 kernel/trace/trace_events.c |   46 +++++++++++++++++++++++++------------------
 1 file changed, 27 insertions(+), 19 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index dec47e7..cb2df3b 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");
-- 
1.7.10.4

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