[PATCH 5/7] ftrace: don't increment @pos in g_start()

Li Zefan
2009-06-24T01:53:20Z

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 large than PAGE_SIZE.

[ Impact: fix missing entries when reading set_graph_function ]

Reviewed-by: Liming Wang <liming.wang@windriver.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
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 561cafc..c06e9ab 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2499,32 +2499,31 @@ 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)
--
1.5.4.rc3