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SubjectRe: [PATCH] lockdep: Avoid /proc/lockdep & lock_stat infinite output
On Mon, Oct 08, 2007 at 06:15:51PM -0700, Tim Pepper wrote:
>
> When a read() requests an amount of data smaller than the amount of data
> that the seq_file's foo_show() outputs, the output starts looping and
> outputs the "stuck" element's data infinitely. There may be multiple
> sequential calls to foo_start(), foo_next()/foo_show(), and foo_stop()
> for a single open with sequential read of the file. The _start() does not
> have to start with the 0th element and _show() might be called multiple
> times in a row for the same element for a given open/read of the seq_file.
>
> static void *l_start(struct seq_file *m, loff_t *pos)
> {
> - struct lock_class *class = m->private;
> + struct lock_class *class;
> + loff_t i = 0;
>
> - if (&class->lock_entry == all_lock_classes.next)
> + if (*pos == 0)
> seq_printf(m, "all lock classes:\n");

Do not generate output outside of ->show() and you won't have these
problems. That's where your infinite output crap comes from.

IOW, NAK - fix the underlying problem.
-
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