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

[tip-bot for Li Zefan]

Commit-ID:  85951842a1020669f0a9eb0f0d1853b41341f097
Gitweb:     http://git.kernel.org/tip/85951842a1020669f0a9eb0f0d1853b41341f097
Author:     Li Zefan <lizf@xxxxxxxxxxxxxx>
AuthorDate: Wed, 24 Jun 2009 09:54:00 +0800
Committer:  Ingo Molnar <mingo@xxxxxxx>
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@xxxxxxxxxxxxx>
Signed-off-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
LKML-Reference: <4A418738.7090401@xxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
 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)
--
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