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SubjectRe: /proc/timer_list and weird behavior with dropbear
On Fri, Jul 19, 2013 at 03:33:24PM -0500, Nathan Zimmer wrote:
> On Fri, Jul 19, 2013 at 07:03:54PM +0200, 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 = {
>
>
> I think this would be an acceptable fix.
> It work file locally. Could you check it out to see if it behaves?
>
> Nate

Forgot the patch last time.
Sorry

diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index 3bdf283..a3620ec 100644
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -305,24 +305,26 @@ static void *timer_list_start(struct seq_file *file, loff_t *offset)
if (!*offset) {
iter->cpu = -1;
iter->now = ktime_to_ns(ktime_get());
- } else if (iter->cpu >= nr_cpu_ids) {
+ } else {
+ iter->cpu = cpumask_next(iter->cpu, cpu_online_mask);
+ if (iter->cpu >= nr_cpu_ids) {
#ifdef CONFIG_GENERIC_CLOCKEVENTS
- if (!iter->second_pass) {
- iter->cpu = -1;
- iter->second_pass = true;
- } else
- return NULL;
+ if (!iter->second_pass) {
+ iter->cpu = -1;
+ iter->second_pass = true;
+ } else
+ return NULL;
#else
- return NULL;
+ return NULL;
#endif
+ }
}
+
return iter;
}

static void *timer_list_next(struct seq_file *file, void *v, loff_t *offset)
{
- struct timer_list_iter *iter = file->private;
- iter->cpu = cpumask_next(iter->cpu, cpu_online_mask);
++*offset;
return timer_list_start(file, offset);
}
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