net/mlx5e: Drop XFRM state lock when modifying flow steering

XFRM state which is changed to be XFRM_STATE_EXPIRED doesn't really
need to hold lock while modifying flow steering rules to drop traffic.

That state can be deleted only and as such mlx5e_ipsec_handle_tx_limit()
work will be canceled anyway and won't run in parallel.

Fixes: b2f7b01 ("net/mlx5e: Simulate missing IPsec TX limits hardware functionality")
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en_accel/ipsec.c

@@ -61,16 +61,19 @@ static void mlx5e_ipsec_handle_tx_limit(struct work_struct *_work)
 	struct mlx5e_ipsec_sa_entry *sa_entry = dwork->sa_entry;
 	struct xfrm_state *x = sa_entry->x;
 
-	spin_lock(&x->lock);
+	if (sa_entry->attrs.drop)
+		return;
+
+	spin_lock_bh(&x->lock);
 	xfrm_state_check_expire(x);
 	if (x->km.state == XFRM_STATE_EXPIRED) {
 		sa_entry->attrs.drop = true;
-		mlx5e_accel_ipsec_fs_modify(sa_entry);
-	}
-	spin_unlock(&x->lock);
+		spin_unlock_bh(&x->lock);
 
-	if (sa_entry->attrs.drop)
+		mlx5e_accel_ipsec_fs_modify(sa_entry);
 		return;
+	}
+	spin_unlock_bh(&x->lock);
 
 	queue_delayed_work(sa_entry->ipsec->wq, &dwork->dwork,
 			   MLX5_IPSEC_RESCHED);