net: sched: flower: insert filter to ht before offloading it to hw
John reports: Recent refactoring of fl_change aims to use the classifier spinlock to avoid the need for rtnl lock. In doing so, the fl_hw_replace_filer() function was moved to before the lock is taken. This can create problems for drivers if duplicate filters are created (commmon in ovs tc offload due to filters being triggered by user-space matches). Drivers registered for such filters will now receive multiple copies of the same rule, each with a different cookie value. This means that the drivers would need to do a full match field lookup to determine duplicates, repeating work that will happen in flower __fl_lookup(). Currently, drivers do not expect to receive duplicate filters. To fix this, verify that filter with same key is not present in flower classifier hash table and insert the new filter to the flower hash table before offloading it to hardware. Implement helper function fl_ht_insert_unique() to atomically verify/insert a filter. This change makes filter visible to fast path at the beginning of fl_change() function, which means it can no longer be freed directly in case of error. Refactor fl_change() error handling code to deallocate the filter with rcu timeout. Fixes: 620da486 ("net: sched: flower: refactor fl_change") Reported-by:John Hurley <john.hurley@netronome.com> Signed-off-by:
Vlad Buslov <vladbu@mellanox.com> Acked-by:
Jiri Pirko <jiri@mellanox.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
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