net/mlx5e: Protect encap hash table with mutex

To remove dependency on rtnl lock, protect encap hash table from concurrent
modifications with new "encap_tbl_lock" mutex. Use the mutex to protect
internal encap entry state from concurrent modification. This is necessary
because a flow can be attached to multiple encap entries simultaneously,
which significantly complicates using finer grained per-entry lock.

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

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index 4e37820..c13db9b 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -1478,33 +1478,51 @@ void mlx5e_tc_update_neigh_used_value(struct mlx5e_neigh_hash_entry *nhe)
        }
 }
 
-void mlx5e_encap_put(struct mlx5e_priv *priv, struct mlx5e_encap_entry *e)
+static void mlx5e_encap_dealloc(struct mlx5e_priv *priv, struct mlx5e_encap_entry *e)
 {
-       if (!refcount_dec_and_test(&e->refcnt))
-               return;
-
        WARN_ON(!list_empty(&e->flows));
        mlx5e_rep_encap_entry_detach(netdev_priv(e->out_dev), e);
 
        if (e->flags & MLX5_ENCAP_ENTRY_VALID)
                mlx5_packet_reformat_dealloc(priv->mdev, e->encap_id);
 
-       hash_del_rcu(&e->encap_hlist);
        kfree(e->encap_header);
        kfree(e);
 }
 
+void mlx5e_encap_put(struct mlx5e_priv *priv, struct mlx5e_encap_entry *e)
+{
+       struct mlx5_eswitch *esw = priv->mdev->priv.eswitch;
+
+       if (!refcount_dec_and_mutex_lock(&e->refcnt, &esw->offloads.encap_tbl_lock))
+               return;
+       hash_del_rcu(&e->encap_hlist);
+       mutex_unlock(&esw->offloads.encap_tbl_lock);
+
+       mlx5e_encap_dealloc(priv, e);
+}
+
 static void mlx5e_detach_encap(struct mlx5e_priv *priv,
                               struct mlx5e_tc_flow *flow, int out_index)
 {
+       struct mlx5e_encap_entry *e = flow->encaps[out_index].e;
+       struct mlx5_eswitch *esw = priv->mdev->priv.eswitch;
+
        /* flow wasn't fully initialized */
-       if (!flow->encaps[out_index].e)
+       if (!e)
                return;
 
+       mutex_lock(&esw->offloads.encap_tbl_lock);
        list_del(&flow->encaps[out_index].list);
-
-       mlx5e_encap_put(priv, flow->encaps[out_index].e);
        flow->encaps[out_index].e = NULL;
+       if (!refcount_dec_and_test(&e->refcnt)) {
+               mutex_unlock(&esw->offloads.encap_tbl_lock);
+               return;
+       }
+       hash_del_rcu(&e->encap_hlist);
+       mutex_unlock(&esw->offloads.encap_tbl_lock);
+
+       mlx5e_encap_dealloc(priv, e);
 }
 
 static void __mlx5e_tc_del_fdb_peer_flow(struct mlx5e_tc_flow *flow)
@@ -2882,6 +2900,7 @@ static int mlx5e_attach_encap(struct mlx5e_priv *priv,
 
        hash_key = hash_encap_info(&key);
 
+       mutex_lock(&esw->offloads.encap_tbl_lock);
        e = mlx5e_encap_get(priv, &key, hash_key);
 
        /* must verify if encap is valid or not */
@@ -2889,8 +2908,10 @@ static int mlx5e_attach_encap(struct mlx5e_priv *priv,
                goto attach_flow;
 
        e = kzalloc(sizeof(*e), GFP_KERNEL);
-       if (!e)
-               return -ENOMEM;
+       if (!e) {
+               err = -ENOMEM;
+               goto out_err;
+       }
 
        refcount_set(&e->refcnt, 1);
        e->tun_info = tun_info;
@@ -2922,10 +2943,12 @@ attach_flow:
        } else {
                *encap_valid = false;
        }
+       mutex_unlock(&esw->offloads.encap_tbl_lock);
 
        return err;
 
 out_err:
+       mutex_unlock(&esw->offloads.encap_tbl_lock);
        kfree(e);
        return err;
 }

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
index 2d734ec..f069240 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.c
@@ -1999,6 +1999,7 @@ int mlx5_eswitch_init(struct mlx5_core_dev *dev)
        if (err)
                goto abort;
 
+       mutex_init(&esw->offloads.encap_tbl_lock);
        hash_init(esw->offloads.encap_tbl);
        mutex_init(&esw->offloads.mod_hdr.lock);
        hash_init(esw->offloads.mod_hdr.hlist);
@@ -2039,6 +2040,7 @@ void mlx5_eswitch_cleanup(struct mlx5_eswitch *esw)
        destroy_workqueue(esw->work_queue);
        esw_offloads_cleanup_reps(esw);
        mutex_destroy(&esw->offloads.mod_hdr.lock);
+       mutex_destroy(&esw->offloads.encap_tbl_lock);
        kfree(esw->vports);
        kfree(esw);
 }

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.h b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.h
index fd63ba4..86db0e9 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/eswitch.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/eswitch.h
@@ -181,6 +181,7 @@ struct mlx5_esw_offload {
        struct mlx5_eswitch_rep *vport_reps;
        struct list_head peer_flows;
        struct mutex peer_mutex;
+       struct mutex encap_tbl_lock; /* protects encap_tbl */
        DECLARE_HASHTABLE(encap_tbl, 8);
        struct mod_hdr_tbl mod_hdr;
        DECLARE_HASHTABLE(termtbl_tbl, 8);