[tip:tracing/urgent] tracing: Reset iterator in t_start()

tip-bot for Li Zefan
2009-06-24T09:47:09Z

Commit-ID: f129e965bef40c6153e4fe505f1e408286213424
Gitweb: http://git.kernel.org/tip/f129e965bef40c6153e4fe505f1e408286213424
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Wed, 24 Jun 2009 09:53:44 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 24 Jun 2009 11:02:51 +0200

tracing: Reset iterator in t_start()

The iterator is m->private, but it's not reset to trace_types in
t_start(). If the output is larger than PAGE_SIZE and t_start()
is called the 2nd time, things will go wrong.

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: <4A418728.5020506@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
kernel/trace/trace.c | 18 ++++--------------
1 files changed, 4 insertions(+), 14 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 076fa6f..3bb3100 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2053,25 +2053,23 @@ static int tracing_open(struct inode *inode, struct file *file)
static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
- struct tracer *t = m->private;
+ struct tracer *t = v;

(*pos)++;

if (t)
t = t->next;

- m->private = t;
-
return t;
}

static void *t_start(struct seq_file *m, loff_t *pos)
{
- struct tracer *t = m->private;
+ struct tracer *t;
loff_t l = 0;

mutex_lock(&trace_types_lock);
- for (; t && l < *pos; t = t_next(m, t, &l))
+ for (t = trace_types; t && l < *pos; t = t_next(m, t, &l))
;

return t;
@@ -2107,18 +2105,10 @@ static struct seq_operations show_traces_seq_ops = {

static int show_traces_open(struct inode *inode, struct file *file)
{
- int ret;
-
if (tracing_disabled)
return -ENODEV;

- ret = seq_open(file, &show_traces_seq_ops);
- if (!ret) {
- struct seq_file *m = file->private_data;
- m->private = trace_types;
- }
-
- return ret;
+ return seq_open(file, &show_traces_seq_ops);
}

static ssize_t