Re: [NET]: gen_estimator deadlock fix

[David Miller <davem@davemloft.net>]

From: Ranko Zivojnovic <ranko@spidernet.net>
Date: Mon, 16 Jul 2007 20:45:05 +0300

> [NET] gen_estimator deadlock fix
> 
> -Fixes ABBA deadlock noted by Patrick McHardy <kaber@trash.net>:
> 
> > There is at least one ABBA deadlock, est_timer() does:
> > read_lock(&est_lock)
> > spin_lock(e->stats_lock) (which is dev->queue_lock)
> >
> > and qdisc_destroy calls htb_destroy under dev->queue_lock, which
> > calls htb_destroy_class, then gen_kill_estimator and this
> > write_locks est_lock.
> 
> To fix the ABBA deadlock the rate estimators are now kept on an rcu list.
> 
> -The est_lock changes the use from protecting the list to protecting
> the update to the 'bstat' pointer in order to avoid NULL dereferencing.
> 
> -The 'interval' member of the gen_estimator structure removed as it is
> not needed.
> 
> Signed-off-by: Ranko Zivojnovic <ranko@spidernet.net>

Applied, thanks.