[tip:tracing/urgent] ftrace: Don't increment @pos in g_start()

tip-bot for Li Zefan
2009-06-24T09:47:27Z

Commit-ID: 85951842a1020669f0a9eb0f0d1853b41341f097
Gitweb: http://git.kernel.org/tip/85951842a1020669f0a9eb0f0d1853b41341f097
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Wed, 24 Jun 2009 09:54:00 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 24 Jun 2009 11:02:52 +0200

ftrace: Don't increment @pos in g_start()

It's wrong to increment @pos in g_start(). It causes some entries
lost when reading set_graph_function, if the output of the file
is larger than PAGE_SIZE.

Reviewed-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A418738.7090401@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
kernel/trace/ftrace.c | 21 ++++++++++-----------
1 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3718d55..cde74b9 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2500,32 +2500,31 @@ int ftrace_graph_count;
unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;

static void *
-g_next(struct seq_file *m, void *v, loff_t *pos)
+__g_next(struct seq_file *m, loff_t *pos)
{
unsigned long *array = m->private;
- int index = *pos;
-
- (*pos)++;

- if (index >= ftrace_graph_count)
+ if (*pos >= ftrace_graph_count)
return NULL;
+ return &array[*pos];
+}

- return &array[index];
+static void *
+g_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ (*pos)++;
+ return __g_next(m, pos);
}

static void *g_start(struct seq_file *m, loff_t *pos)
{
- void *p = NULL;
-
mutex_lock(&graph_lock);

/* Nothing, tell g_show to print all functions are enabled */
if (!ftrace_graph_count && !*pos)
return (void *)1;

- p = g_next(m, p, pos);
-
- return p;
+ return __g_next(m, pos);
}

static void g_stop(struct seq_file *m, void *p)