tracing: Do not reset *pos in set_ftrace_filter

After the filtered functions are read, the probed functions are read
from the hash in set_ftrace_filter. When the hashed probed functions
are read, the *pos passed in is reset. Instead of modifying the pos
given to the read function, just record the pos where the filtered
functions ended and subtract from that.

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

1 files changed, 6 insertions, 2 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index fa7ece649fe1..585ea27025b1 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1368,6 +1368,7 @@ enum {
 #define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
 
 struct ftrace_iterator {
+        loff_t                  func_pos;
         struct ftrace_page      *pg;
         int                     hidx;
         int                     idx;
@@ -1418,12 +1419,15 @@ static void *t_hash_start(struct seq_file *m, loff_t *pos)
         loff_t l;
 
         if (!(iter->flags & FTRACE_ITER_HASH))
-                *pos = 0;
+                iter->func_pos = *pos;
+
+        if (iter->func_pos > *pos)
+                return NULL;
 
         iter->flags |= FTRACE_ITER_HASH;
 
         iter->hidx = 0;
-        for (l = 0; l <= *pos; ) {
+        for (l = 0; l <= (*pos - iter->func_pos); ) {
                 p = t_hash_next(m, p, &l);
                 if (!p)
                         break;