RDMA/core: Allow drivers to disable restrack DB

Driver QP types are special case with no IBTA restrictions. For example,
EFA implemented creation of this QP type as regular one, while mlx5
separated create to two step: create and modify. That separation causes to
the situation where DC QP (mlx5) is always added to the same xarray index
zero.

This change allows to drivers like mlx5 simply disable restrack DB
tracking, but it doesn't disable kref on the memory.

Fixes: 52e0a118a2 ("RDMA/restrack: Track driver QP types in resource tracker")
Link: https://lore.kernel.org/r/20201117070148.1974114-3-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/counters.c

@@ -285,7 +285,7 @@ int rdma_counter_bind_qp_auto(struct ib_qp *qp, u8 port)
 	struct rdma_counter *counter;
 	int ret;
 
-	if (!qp->res.valid || rdma_is_kernel_res(&qp->res))
+	if (!rdma_restrack_is_tracked(&qp->res) || rdma_is_kernel_res(&qp->res))
 		return 0;
 
 	if (!rdma_is_port_valid(dev, port))

drivers/infiniband/core/restrack.c

@@ -221,11 +221,14 @@ void rdma_restrack_add(struct rdma_restrack_entry *res)
 {
 	struct ib_device *dev = res_to_dev(res);
 	struct rdma_restrack_root *rt;
-	int ret;
+	int ret = 0;
 
 	if (!dev)
 		return;
 
+	if (res->no_track)
+		goto out;
+
 	rt = &dev->res[res->type];
 
 	if (res->type == RDMA_RESTRACK_QP) {
@@ -253,6 +256,7 @@ void rdma_restrack_add(struct rdma_restrack_entry *res)
 				      &rt->next_id, GFP_KERNEL);
 	}
 
+out:
 	if (!ret)
 		res->valid = true;
 }
@@ -325,6 +329,9 @@ void rdma_restrack_del(struct rdma_restrack_entry *res)
 		return;
 	}
 
+	if (res->no_track)
+		goto out;
+
 	dev = res_to_dev(res);
 	if (WARN_ON(!dev))
 		return;
@@ -335,8 +342,9 @@ void rdma_restrack_del(struct rdma_restrack_entry *res)
 	if (res->type == RDMA_RESTRACK_MR || res->type == RDMA_RESTRACK_QP)
 		return;
 	WARN_ON(old != res);
-	res->valid = false;
 
+out:
+	res->valid = false;
 	rdma_restrack_put(res);
 	wait_for_completion(&res->comp);
 }

drivers/infiniband/hw/mlx4/qp.c

@@ -1561,6 +1561,11 @@ static int _mlx4_ib_create_qp(struct ib_pd *pd, struct mlx4_ib_qp *qp,
 		if (err)
 			return err;
 
+		if (init_attr->create_flags &
+		    (MLX4_IB_SRIOV_SQP | MLX4_IB_SRIOV_TUNNEL_QP))
+			/* Internal QP created with ib_create_qp */
+			rdma_restrack_no_track(&qp->ibqp.res);
+
 		qp->port	= init_attr->port_num;
 		qp->ibqp.qp_num = init_attr->qp_type == IB_QPT_SMI ? 0 :
 			init_attr->create_flags & MLX4_IB_QP_CREATE_ROCE_V2_GSI ? sqpn : 1;

drivers/infiniband/hw/mlx5/qp.c

@@ -2410,7 +2410,7 @@ static int create_dct(struct mlx5_ib_dev *dev, struct ib_pd *pd,
 	}
 
 	qp->state = IB_QPS_RESET;
-
+	rdma_restrack_no_track(&qp->ibqp.res);
 	return 0;
 }
 

include/rdma/restrack.h

@@ -68,6 +68,14 @@ struct rdma_restrack_entry {
 	 * As an example for that, see mlx5 QPs with type MLX5_IB_QPT_HW_GSI
 	 */
 	bool			valid;
+	/**
+	 * @no_track: don't add this entry to restrack DB
+	 *
+	 * This field is used to mark an entry that doesn't need to be added to
+	 * internal restrack DB and presented later to the users at the nldev
+	 * query stage.
+	 */
+	u8			no_track : 1;
 	/*
 	 * @kref: Protect destroy of the resource
 	 */
@@ -145,4 +153,20 @@ int rdma_nl_stat_hwcounter_entry(struct sk_buff *msg, const char *name,
 struct rdma_restrack_entry *rdma_restrack_get_byid(struct ib_device *dev,
 						   enum rdma_restrack_type type,
 						   u32 id);
+
+/**
+ * rdma_restrack_no_track() - don't add resource to the DB
+ * @res: resource entry
+ *
+ * Every user of thie API should be cross examined.
+ * Probaby you don't need to use this function.
+ */
+static inline void rdma_restrack_no_track(struct rdma_restrack_entry *res)
+{
+	res->no_track = true;
+}
+static inline bool rdma_restrack_is_tracked(struct rdma_restrack_entry *res)
+{
+	return !res->no_track;
+}
 #endif /* _RDMA_RESTRACK_H_ */