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SubjectRe: [PATCH 6/8] padata: Use a timer to handle the reorder queues
On Thu, 29 Apr 2010 14:43:37 +0200
Steffen Klassert <steffen.klassert@secunet.com> wrote:

> padata_get_next had a bogus check that returned always true,
> so the try_again loop in padata_reorder was never taken.

A better changelog would have told us what this "bogus check" _is_.

> This can lead to object leaks in some rare cases.

And a better changelog would describe those leaks!

> This patch
> implements a timer that processes the reorder queues if noone
> else does it in appropriate time.

Under what circumstances would "noone else do it in appropriate time"?
Would that be a bug, or what?

> @@ -273,13 +274,22 @@ try_again:
>
> spin_unlock_bh(&pd->lock);
>
> - if (atomic_read(&pd->reorder_objects))
> - goto try_again;
> + if (atomic_read(&pd->reorder_objects)
> + && !(pinst->flags & PADATA_RESET))
> + mod_timer(&pd->timer, jiffies + HZ);
> + else
> + del_timer(&pd->timer);
>
> -out:
> return;
> }

I'd feel more comfortable if the above was in the locked region. Is
there a race whereby another CPU can set pd->reorder_objects, but we
forgot to arm the timer?




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