ftrace: Remove unused function ftrace_arch_read_dyn_info()

ftrace_arch_read_dyn_info() was used so that archs could add its own debug
information into the dyn_ftrace_total_info in the tracefs file system. That
file is for debugging usage of dynamic ftrace. No arch uses that function
anymore, so just get rid of it.

This also allows for tracing_read_dyn_info() to be cleaned up a bit.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -6737,33 +6737,18 @@ static const struct file_operations tracing_stats_fops = {
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
-int __weak ftrace_arch_read_dyn_info(char *buf, int size)
-{
-	return 0;
-}
-
 static ssize_t
 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);
+	char buf[64]; /* Not too big for a shallow stack */
 	int r;
 
-	mutex_lock(&dyn_info_mutex);
-	r = sprintf(buf, "%ld ", *p);
-
-	r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
+	r = scnprintf(buf, 63, "%ld", *p);
 	buf[r++] = '\n';
 
-	r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
-
-	mutex_unlock(&dyn_info_mutex);
-
-	return r;
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
 }
 
 static const struct file_operations tracing_dyn_info_fops = {