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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: Håkon Bugge <haakon.bugge@oracle.com>
Acked-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Håkon Bugge 2021-03-31 20:43:13 +02:00 committed by Jason Gunthorpe
parent 8166e00905
commit 3aeffc46af
3 changed files with 45 additions and 0 deletions
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41
drivers/infiniband/core/cma.c
View File

@ -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)
{

2
drivers/infiniband/core/cma_priv.h
View File

@ -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;
/*

2
include/rdma/rdma_cm.h
View File

@ -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.