tracing: Fix file mode of free_buffer

Commit 4f271a2a60c748599b30bb4dafff30d770439b96
(tracing: Add a proc file to stop tracing and free buffer)
implement a method to free up ring buffer in kernel memory
in the release code path of free_buffer's fd.

Then we don't need read/write support for free_buffer,
indeed we just have a dummy write fop, and don't implement read fop.

So the 0200 is more reasonable file mode for free_buffer than
the current file mode 0644.

Link: http://lkml.kernel.org/r/20130526085201.GA3183@udknight
Acked-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Acked-by: David Sharp <dhsharp@google.com>
Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 1a41023a1f88e03cb6ee79e0b7c46991857e90ab..5f4a09c12e0ba09dd2b313ce1eb2d8c14256efa8 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5935,7 +5935,7 @@ init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer)
        trace_create_file("buffer_total_size_kb", 0444, d_tracer,
                          tr, &tracing_total_entries_fops);
 
-       trace_create_file("free_buffer", 0644, d_tracer,
+       trace_create_file("free_buffer", 0200, d_tracer,
                          tr, &tracing_free_buffer_fops);
 
        trace_create_file("trace_marker", 0220, d_tracer,