Re: [PATCH] tracing: fix warning in s_next

From: Steven Rostedt
Date: Tue Mar 02 2010 - 09:33:53 EST


On Tue, 2010-03-02 at 17:54 +0800, Lai Jiangshan wrote:
> This warning in s_next() can be triggered by lseek():
> [<c018b3f7>] ? s_next+0x77/0x80
> [<c013e3c1>] warn_slowpath_common+0x81/0xa0
> [<c018b3f7>] ? s_next+0x77/0x80
> [<c013e3fa>] warn_slowpath_null+0x1a/0x20
> [<c018b3f7>] s_next+0x77/0x80
> [<c01efa77>] traverse+0x117/0x200
> [<c01eff13>] seq_lseek+0xa3/0x120
> [<c01efe70>] ? seq_lseek+0x0/0x120
> [<c01d7081>] vfs_llseek+0x41/0x50
> [<c01d8116>] sys_llseek+0x66/0xa0
> [<c0102bd0>] sysenter_do_call+0x12/0x26
>
> It is because s_start() calls s_next() without reset leftover.

Applied, Thanks!

-- Steve

>
> Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
> ---
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 032c57c..5edf410 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -1703,6 +1703,7 @@ static void *s_start(struct seq_file *m, loff_t *pos)
>
> ftrace_enable_cpu();
>
> + iter->leftover = 0;
> for (p = iter; p && l < *pos; p = s_next(m, p, &l))
> ;
>


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