ftrace: Narrow down the protected area of graph_lock

The parser set up is just a generic utility that uses local variables
allocated by the function. There's no need to hold the graph_lock for
this set up.

This also makes the code simpler.

Link: http://lkml.kernel.org/r/1381739066-7531-4-git-send-email-namhyung@kernel.org

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 9 insertions, 13 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0ff3449b4272..26a229ab0c19 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3973,37 +3973,33 @@ ftrace_graph_write(struct file *file, const char __user *ubuf,
                    size_t cnt, loff_t *ppos)
 {
         struct trace_parser parser;
-        ssize_t read, ret;
+        ssize_t read, ret = 0;
         struct ftrace_graph_data *fgd = file->private_data;
 
         if (!cnt)
                 return 0;
 
-        mutex_lock(&graph_lock);
-
-        if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX)) {
-                ret = -ENOMEM;
-                goto out_unlock;
-        }
+        if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX))
+                return -ENOMEM;
 
         read = trace_get_user(&parser, ubuf, cnt, ppos);
 
         if (read >= 0 && trace_parser_loaded((&parser))) {
                 parser.buffer[parser.idx] = 0;
 
+                mutex_lock(&graph_lock);
+
                 /* we allow only one expression at a time */
                 ret = ftrace_set_func(fgd->table, fgd->count, fgd->size,
                                       parser.buffer);
-                if (ret)
-                        goto out_free;
+
+                mutex_unlock(&graph_lock);
         }
 
-        ret = read;
+        if (!ret)
+                ret = read;
 
-out_free:
         trace_parser_put(&parser);
-out_unlock:
-        mutex_unlock(&graph_lock);
 
         return ret;
 }