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>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0ff3449b42729d5715f78de0d0b12a7d7a3e609f..26a229ab0c199fb8ac5b827e8c28e9cb97218ccb 100644 (file)
--- 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;
 }