Commit 3aeffc46 authored by Håkon Bugge's avatar Håkon Bugge Committed by Jason Gunthorpe
Browse files

IB/cma: Introduce rdma_set_min_rnr_timer() 

Introduce the ability for kernel ULPs to adjust the minimum RNR Retry
timer. The INIT -> RTR transition executed by RDMA CM will be used for
this adjustment. This avoids an additional ib_modify_qp() call.

rdma_set_min_rnr_timer() must be called before the call to rdma_connect()
on the active side and before the call to rdma_accept() on the passive
side.

The default value of RNR Retry timer is zero, which translates to 655
ms. When the receiver is not ready to accept a send messages, it encodes
the RNR Retry timer value in the NAK. The requestor will then wait at
least the specified time value before retrying the send.

The 5-bit value to be supplied to the rdma_set_min_rnr_timer() is
documented in IBTA Table 45: "Encoding for RNR NAK Timer Field".

Link: https://lore.kernel.org/r/1617216194-12890-2-git-send-email-haakon.bugge@oracle.com


Signed-off-by: default avatarHåkon Bugge <haakon.bugge@oracle.com>
Acked-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent 8166e009

drivers/infiniband/core/cma.c

+41 −0
Original line number Diff line number Diff line
@@ -843,6 +843,7 @@ __rdma_create_id(struct net *net, rdma_cm_event_handler event_handler, 
	id_priv->id.qp_type = qp_type;

	id_priv->tos_set = false;

	id_priv->timeout_set = false;

	id_priv->min_rnr_timer_set = false;

	id_priv->gid_type = IB_GID_TYPE_IB;

	spin_lock_init(&id_priv->lock);

	mutex_init(&id_priv->qp_mutex);
@@ -1133,6 +1134,9 @@ int rdma_init_qp_attr(struct rdma_cm_id *id, struct ib_qp_attr *qp_attr, 
	if ((*qp_attr_mask & IB_QP_TIMEOUT) && id_priv->timeout_set)

		qp_attr->timeout = id_priv->timeout;



	if ((*qp_attr_mask & IB_QP_MIN_RNR_TIMER) && id_priv->min_rnr_timer_set)

		qp_attr->min_rnr_timer = id_priv->min_rnr_timer;



	return ret;

}

EXPORT_SYMBOL(rdma_init_qp_attr);
@@ -2608,6 +2612,43 @@ int rdma_set_ack_timeout(struct rdma_cm_id *id, u8 timeout) 
}

EXPORT_SYMBOL(rdma_set_ack_timeout);



/**

 * rdma_set_min_rnr_timer() - Set the minimum RNR Retry timer of the

 *			      QP associated with a connection identifier.

 * @id: Communication identifier to associated with service type.

 * @min_rnr_timer: 5-bit value encoded as Table 45: "Encoding for RNR NAK

 *		   Timer Field" in the IBTA specification.

 *

 * This function should be called before rdma_connect() on active

 * side, and on passive side before rdma_accept(). The timer value

 * will be associated with the local QP. When it receives a send it is

 * not read to handle, typically if the receive queue is empty, an RNR

 * Retry NAK is returned to the requester with the min_rnr_timer

 * encoded. The requester will then wait at least the time specified

 * in the NAK before retrying. The default is zero, which translates

 * to a minimum RNR Timer value of 655 ms.

 *

 * Return: 0 for success

 */

int rdma_set_min_rnr_timer(struct rdma_cm_id *id, u8 min_rnr_timer)

{

	struct rdma_id_private *id_priv;



	/* It is a five-bit value */

	if (min_rnr_timer & 0xe0)

		return -EINVAL;



	if (WARN_ON(id->qp_type != IB_QPT_RC && id->qp_type != IB_QPT_XRC_TGT))

		return -EINVAL;



	id_priv = container_of(id, struct rdma_id_private, id);

	id_priv->min_rnr_timer = min_rnr_timer;

	id_priv->min_rnr_timer_set = true;



	return 0;

}

EXPORT_SYMBOL(rdma_set_min_rnr_timer);



static void cma_query_handler(int status, struct sa_path_rec *path_rec,

			      void *context)

{

drivers/infiniband/core/cma_priv.h

+2 −0
Original line number Diff line number Diff line
@@ -86,9 +86,11 @@ struct rdma_id_private { 
	u8			tos;

	u8			tos_set:1;

	u8                      timeout_set:1;

	u8			min_rnr_timer_set:1;

	u8			reuseaddr;

	u8			afonly;

	u8			timeout;

	u8			min_rnr_timer;

	enum ib_gid_type	gid_type;



	/*

include/rdma/rdma_cm.h

+2 −0
Original line number Diff line number Diff line
@@ -331,6 +331,8 @@ int rdma_set_reuseaddr(struct rdma_cm_id *id, int reuse); 
int rdma_set_afonly(struct rdma_cm_id *id, int afonly);



int rdma_set_ack_timeout(struct rdma_cm_id *id, u8 timeout);



int rdma_set_min_rnr_timer(struct rdma_cm_id *id, u8 min_rnr_timer);

 /**

 * rdma_get_service_id - Return the IB service ID for a specified address.

 * @id: Communication identifier associated with the address.