trace_stat: Fix missing entry in stat file

One entry is missing in the output of a stat file.

The cause is, when stat_seq_start() is called the 2nd time, we
should start from the (pos-1)th elem in the rbtree but not pos,
because pos == 0 is the header.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A891A65.70009@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c
index 07c60b09258f0ddd68542bf4b28b41d8ae34f654..a4bb239eb9874a1a6efe7703a303a7e103c4c977 100644 (file)
--- a/kernel/trace/trace_stat.c
+++ b/kernel/trace/trace_stat.c
@@ -203,17 +203,21 @@ static void *stat_seq_start(struct seq_file *s, loff_t *pos)
 {
        struct stat_session *session = s->private;
        struct rb_node *node;
+       int n = *pos;
        int i;
 
        /* Prevent from tracer switch or rbtree modification */
        mutex_lock(&session->stat_mutex);
 
        /* If we are in the beginning of the file, print the headers */
-       if (!*pos && session->ts->stat_headers)
-               return SEQ_START_TOKEN;
+       if (session->ts->stat_headers) {
+               if (n == 0)
+                       return SEQ_START_TOKEN;
+               n--;
+       }
 
        node = rb_first(&session->stat_root);
-       for (i = 0; node && i < *pos; i++)
+       for (i = 0; node && i < n; i++)
                node = rb_next(node);
 
        return node;