Re: /proc/timer_list and weird behavior with dropbear

From: Nathan Zimmer
Date: Fri Jul 19 2013 - 15:05:29 EST


On 07/19/2013 12:03 PM, Holger Hans Peter Freyther wrote:
On Fri, Jul 19, 2013 at 10:45:15AM -0500, Nathan Zimmer wrote:

I hadn't noticed anything.
Let me try your program and see what I may have missed.
Hi,

I neither know the semantics of the timer_list nor how to use
seq_file correctly. What happens is that timer_list_next will only
be called once. This means that iter->cpu will never be increased.

This just moves to the next CPU when stop is called (e.g. nothing
was added once the print_tickdevice was printed). Do you think
this could be correct?



diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index 3bdf283..8d36a3d 100644
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -327,8 +327,10 @@ static void *timer_list_next(struct seq_file *file, void *v, loff_t *offset)
return timer_list_start(file, offset);
}
-static void timer_list_stop(struct seq_file *seq, void *v)
+static void timer_list_stop(struct seq_file *file, void *v)
{
+ struct timer_list_iter *iter = file->private;
+ iter->cpu = cpumask_next(iter->cpu, cpu_online_mask);
}
static const struct seq_operations timer_list_sops = {

That certainly does make the issue go away.
I think a better solution would be to have an increment in the timer_list_start.

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