ftrace: nmi safe code clean ups

Impact: cleanup

This patch cleans up the NMI safe code for dynamic ftrace as suggested
by Andrew Morton.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index bc36feb..7f86067 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2815,10 +2815,6 @@
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
-#define DYN_INFO_BUF_SIZE 1023
-static char ftrace_dyn_info_buffer[DYN_INFO_BUF_SIZE+1];
-static DEFINE_MUTEX(dyn_info_mutex);
-
 int __weak ftrace_arch_read_dyn_info(char *buf, int size)
 {
 	return 0;
@@ -2828,14 +2824,17 @@
 tracing_read_dyn_info(struct file *filp, char __user *ubuf,
 		  size_t cnt, loff_t *ppos)
 {
+	static char ftrace_dyn_info_buffer[1024];
+	static DEFINE_MUTEX(dyn_info_mutex);
 	unsigned long *p = filp->private_data;
 	char *buf = ftrace_dyn_info_buffer;
+	int size = ARRAY_SIZE(ftrace_dyn_info_buffer);
 	int r;
 
 	mutex_lock(&dyn_info_mutex);
 	r = sprintf(buf, "%ld ", *p);
 
-	r += ftrace_arch_read_dyn_info(buf+r, DYN_INFO_BUF_SIZE-r);
+	r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
 	buf[r++] = '\n';
 
 	r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);