ftrace: state that all functions are enabled in set_ftrace_filter

Impact: clean up, make set_ftrace_filter less confusing

The set_ftrace_filter shows only the functions that will be traced.
But when it is empty, it will trace all functions. This can be a bit
confusing.

This patch makes set_ftrace_filter show:

  #### all functions enabled ####

When all functions will be traced, and we do not filter only a select
few.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 1796e018fbff..369fb78bd4ab 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -773,6 +773,7 @@ enum {
         FTRACE_ITER_CONT        = (1 << 1),
         FTRACE_ITER_NOTRACE     = (1 << 2),
         FTRACE_ITER_FAILURES    = (1 << 3),
+        FTRACE_ITER_PRINTALL    = (1 << 4),
 };
 
 #define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
@@ -794,6 +795,9 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
 
         (*pos)++;
 
+        if (iter->flags & FTRACE_ITER_PRINTALL)
+                return NULL;
+
         /* should not be called from interrupt context */
         spin_lock(&ftrace_lock);
  retry:
@@ -834,6 +838,19 @@ static void *t_start(struct seq_file *m, loff_t *pos)
         struct ftrace_iterator *iter = m->private;
         void *p = NULL;
 
+        /*
+         * For set_ftrace_filter reading, if we have the filter
+         * off, we can short cut and just print out that all
+         * functions are enabled.
+         */
+        if (iter->flags & FTRACE_ITER_FILTER && !ftrace_filtered) {
+                if (*pos > 0)
+                        return NULL;
+                iter->flags |= FTRACE_ITER_PRINTALL;
+                (*pos)++;
+                return iter;
+        }
+
         if (*pos > 0) {
                 if (iter->idx < 0)
                         return p;
@@ -852,9 +869,15 @@ static void t_stop(struct seq_file *m, void *p)
 
 static int t_show(struct seq_file *m, void *v)
 {
+        struct ftrace_iterator *iter = m->private;
         struct dyn_ftrace *rec = v;
         char str[KSYM_SYMBOL_LEN];
 
+        if (iter->flags & FTRACE_ITER_PRINTALL) {
+                seq_printf(m, "#### all functions enabled ####\n");
+                return 0;
+        }
+
         if (!rec)
                 return 0;