[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> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Adrian Bunk <bunk@kernel.org>
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