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".
Signed-off-by: Håkon Bugge <haakon.bugge@xxxxxxxxxx>
Acked-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
drivers/infiniband/core/cma.c | 41 ++++++++++++++++++++++++++++++++++++++
drivers/infiniband/core/cma_priv.h | 2 ++
include/rdma/rdma_cm.h | 2 ++
3 files changed, 45 insertions(+)
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 9409651..5ce097d 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -852,6 +852,7 @@ static void cma_id_put(struct rdma_id_private *id_priv)
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);
@@ -1141,6 +1142,9 @@ 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);
@@ -2615,6 +2619,43 @@ 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 (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)
{
diff --git a/drivers/infiniband/core/cma_priv.h b/drivers/infiniband/core/cma_priv.h
index caece96..bf83d32 100644
--- a/drivers/infiniband/core/cma_priv.h
+++ b/drivers/infiniband/core/cma_priv.h
@@ -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;
/*
diff --git a/include/rdma/rdma_cm.h b/include/rdma/rdma_cm.h
index 32a67af..8b0f66e 100644
--- a/include/rdma/rdma_cm.h
+++ b/include/rdma/rdma_cm.h
@@ -331,6 +331,8 @@ int rdma_join_multicast(struct rdma_cm_id *id, struct sockaddr *addr,
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.
--
1.8.3.1
