net/mlx5e: Always take reference to neigh entry

Neigh entry has reference counter, however it is only used when scheduling
neigh update event. In all other cases reference to neigh entry is not
taken while working with it. Neigh code relies on synchronization provided
by rtnl lock and uses encap list size as implicit reference counter.

To remove dependency on rtnl lock, always take reference to neigh entry
while using it. Remove neigh entry from hash table and delete it only when
reference counter reaches zero. This can result spurious neigh update
events, when there is an event on entry that has zero encaps attached.
However, such events are rare and properly handled by neigh update handler.

Extend encap entry with reference to neigh hash entry in order to be able
to directly release it when encap is detached, instead of lookup nhe by key
through hash table. Extend nhe with reference to device priv structure to
guarantee correctness when nhe is used with stack devices, bond setup, in
which case it is non-trivial to determine correct device when releasing the
nhe.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Reviewed-by: Jianbo Liu <jianbol@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.h b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.h
index 8ac96727cad8..f5bc9772be98 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.h
@@ -110,6 +110,7 @@ struct mlx5e_neigh {
 struct mlx5e_neigh_hash_entry {
 	struct rhash_head rhash_node;
 	struct mlx5e_neigh m_neigh;
+	struct mlx5e_priv *priv;
 
 	/* Save the neigh hash entry in a list on the representor in
 	 * addition to the hash table. In order to iterate easily over the
@@ -145,6 +146,8 @@ enum {
 };
 
 struct mlx5e_encap_entry {
+	/* attached neigh hash entry */
+	struct mlx5e_neigh_hash_entry *nhe;
 	/* neigh hash entry list of encaps sharing the same neigh */
 	struct list_head encap_list;
 	struct mlx5e_neigh m_neigh;