IB/cm: Include HCA ACK delay in local ACK timeout

The IB CM should include the HCA ACK delay when calculating the local
ACK timeout value to use for RC QPs.  If the HCA ACK delay is large
enough relative to the packet life time, then if it is not taken into
account, the calculated timeout value ends up being too small, which
can result in "retry exceeded" errors.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 57 insertions, 14 deletions

diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
index 16181d655854..c7007c45889a 100644
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -87,6 +87,7 @@ struct cm_port {
 struct cm_device {
 	struct list_head list;
 	struct ib_device *device;
+	u8 ack_delay;
 	struct cm_port port[0];
 };
 
@@ -95,7 +96,7 @@ struct cm_av {
 	union ib_gid dgid;
 	struct ib_ah_attr ah_attr;
 	u16 pkey_index;
-	u8 packet_life_time;
+	u8 timeout;
 };
 
 struct cm_work {
@@ -154,6 +155,7 @@ struct cm_id_private {
 	u8 retry_count;
 	u8 rnr_retry_count;
 	u8 service_timeout;
+	u8 target_ack_delay;
 
 	struct list_head work_list;
 	atomic_t work_count;
@@ -293,7 +295,7 @@ static int cm_init_av_by_path(struct ib_sa_path_rec *path, struct cm_av *av)
 	av->port = port;
 	ib_init_ah_from_path(cm_dev->device, port->port_num, path,
 			     &av->ah_attr);
-	av->packet_life_time = path->packet_life_time;
+	av->timeout = path->packet_life_time + 1;
 	return 0;
 }
 
@@ -643,6 +645,25 @@ static inline int cm_convert_to_ms(int iba_time)
 	return 1 << max(iba_time - 8, 0);
 }
 
+/*
+ * calculate: 4.096x2^ack_timeout = 4.096x2^ack_delay + 2x4.096x2^life_time
+ * Because of how ack_timeout is stored, adding one doubles the timeout.
+ * To avoid large timeouts, select the max(ack_delay, life_time + 1), and
+ * increment it (round up) only if the other is within 50%.
+ */
+static u8 cm_ack_timeout(u8 ca_ack_delay, u8 packet_life_time)
+{
+	int ack_timeout = packet_life_time + 1;
+
+	if (ack_timeout >= ca_ack_delay)
+		ack_timeout += (ca_ack_delay >= (ack_timeout - 1));
+	else
+		ack_timeout = ca_ack_delay +
+			      (ack_timeout >= (ca_ack_delay - 1));
+
+	return min(31, ack_timeout);
+}
+
 static void cm_cleanup_timewait(struct cm_timewait_info *timewait_info)
 {
 	if (timewait_info->inserted_remote_id) {
@@ -686,7 +707,7 @@ static void cm_enter_timewait(struct cm_id_private *cm_id_priv)
 	 * timewait before notifying the user that we've exited timewait.
 	 */
 	cm_id_priv->id.state = IB_CM_TIMEWAIT;
-	wait_time = cm_convert_to_ms(cm_id_priv->av.packet_life_time + 1);
+	wait_time = cm_convert_to_ms(cm_id_priv->av.timeout);
 	queue_delayed_work(cm.wq, &cm_id_priv->timewait_info->work.work,
 			   msecs_to_jiffies(wait_time));
 	cm_id_priv->timewait_info = NULL;
@@ -908,7 +929,8 @@ static void cm_format_req(struct cm_req_msg *req_msg,
 	cm_req_set_primary_sl(req_msg, param->primary_path->sl);
 	cm_req_set_primary_subnet_local(req_msg, 1); /* local only... */
 	cm_req_set_primary_local_ack_timeout(req_msg,
-		min(31, param->primary_path->packet_life_time + 1));
+		cm_ack_timeout(cm_id_priv->av.port->cm_dev->ack_delay,
+			       param->primary_path->packet_life_time));
 
 	if (param->alternate_path) {
 		req_msg->alt_local_lid = param->alternate_path->slid;
@@ -923,7 +945,8 @@ static void cm_format_req(struct cm_req_msg *req_msg,
 		cm_req_set_alt_sl(req_msg, param->alternate_path->sl);
 		cm_req_set_alt_subnet_local(req_msg, 1); /* local only... */
 		cm_req_set_alt_local_ack_timeout(req_msg,
-			min(31, param->alternate_path->packet_life_time + 1));
+			cm_ack_timeout(cm_id_priv->av.port->cm_dev->ack_delay,
+				       param->alternate_path->packet_life_time));
 	}
 
 	if (param->private_data && param->private_data_len)
@@ -1433,7 +1456,8 @@ static void cm_format_rep(struct cm_rep_msg *rep_msg,
 	cm_rep_set_starting_psn(rep_msg, cpu_to_be32(param->starting_psn));
 	rep_msg->resp_resources = param->responder_resources;
 	rep_msg->initiator_depth = param->initiator_depth;
-	cm_rep_set_target_ack_delay(rep_msg, param->target_ack_delay);
+	cm_rep_set_target_ack_delay(rep_msg,
+				    cm_id_priv->av.port->cm_dev->ack_delay);
 	cm_rep_set_failover(rep_msg, param->failover_accepted);
 	cm_rep_set_flow_ctrl(rep_msg, param->flow_control);
 	cm_rep_set_rnr_retry_count(rep_msg, param->rnr_retry_count);
@@ -1680,6 +1704,13 @@ static int cm_rep_handler(struct cm_work *work)
 	cm_id_priv->responder_resources = rep_msg->initiator_depth;
 	cm_id_priv->sq_psn = cm_rep_get_starting_psn(rep_msg);
 	cm_id_priv->rnr_retry_count = cm_rep_get_rnr_retry_count(rep_msg);
+	cm_id_priv->target_ack_delay = cm_rep_get_target_ack_delay(rep_msg);
+	cm_id_priv->av.timeout =
+			cm_ack_timeout(cm_id_priv->target_ack_delay,
+				       cm_id_priv->av.timeout - 1);
+	cm_id_priv->alt_av.timeout =
+			cm_ack_timeout(cm_id_priv->target_ack_delay,
+				       cm_id_priv->alt_av.timeout - 1);
 
 	/* todo: handle peer_to_peer */
 
@@ -2291,7 +2322,7 @@ static int cm_mra_handler(struct cm_work *work)
 	work->cm_event.param.mra_rcvd.service_timeout =
 					cm_mra_get_service_timeout(mra_msg);
 	timeout = cm_convert_to_ms(cm_mra_get_service_timeout(mra_msg)) +
-		  cm_convert_to_ms(cm_id_priv->av.packet_life_time);
+		  cm_convert_to_ms(cm_id_priv->av.timeout);
 
 	spin_lock_irq(&cm_id_priv->lock);
 	switch (cm_id_priv->id.state) {
@@ -2363,7 +2394,8 @@ static void cm_format_lap(struct cm_lap_msg *lap_msg,
 	cm_lap_set_sl(lap_msg, alternate_path->sl);
 	cm_lap_set_subnet_local(lap_msg, 1); /* local only... */
 	cm_lap_set_local_ack_timeout(lap_msg,
-		min(31, alternate_path->packet_life_time + 1));
+		cm_ack_timeout(cm_id_priv->av.port->cm_dev->ack_delay,
+			       alternate_path->packet_life_time));
 
 	if (private_data && private_data_len)
 		memcpy(lap_msg->private_data, private_data, private_data_len);
@@ -2394,6 +2426,9 @@ int ib_send_cm_lap(struct ib_cm_id *cm_id,
 	ret = cm_init_av_by_path(alternate_path, &cm_id_priv->alt_av);
 	if (ret)
 		goto out;
+	cm_id_priv->alt_av.timeout =
+			cm_ack_timeout(cm_id_priv->target_ack_delay,
+				       cm_id_priv->alt_av.timeout - 1);
 
 	ret = cm_alloc_msg(cm_id_priv, &msg);
 	if (ret)
@@ -3248,8 +3283,7 @@ static int cm_init_qp_rtr_attr(struct cm_id_private *cm_id_priv,
 			*qp_attr_mask |= IB_QP_ALT_PATH;
 			qp_attr->alt_port_num = cm_id_priv->alt_av.port->port_num;
 			qp_attr->alt_pkey_index = cm_id_priv->alt_av.pkey_index;
-			qp_attr->alt_timeout =
-					cm_id_priv->alt_av.packet_life_time + 1;
+			qp_attr->alt_timeout = cm_id_priv->alt_av.timeout;
 			qp_attr->alt_ah_attr = cm_id_priv->alt_av.ah_attr;
 		}
 		ret = 0;
@@ -3287,8 +3321,7 @@ static int cm_init_qp_rts_attr(struct cm_id_private *cm_id_priv,
 				*qp_attr_mask |= IB_QP_TIMEOUT | IB_QP_RETRY_CNT |
 						 IB_QP_RNR_RETRY |
 						 IB_QP_MAX_QP_RD_ATOMIC;
-				qp_attr->timeout =
-					cm_id_priv->av.packet_life_time + 1;
+				qp_attr->timeout = cm_id_priv->av.timeout;
 				qp_attr->retry_cnt = cm_id_priv->retry_count;
 				qp_attr->rnr_retry = cm_id_priv->rnr_retry_count;
 				qp_attr->max_rd_atomic =
@@ -3302,8 +3335,7 @@ static int cm_init_qp_rts_attr(struct cm_id_private *cm_id_priv,
 			*qp_attr_mask = IB_QP_ALT_PATH | IB_QP_PATH_MIG_STATE;
 			qp_attr->alt_port_num = cm_id_priv->alt_av.port->port_num;
 			qp_attr->alt_pkey_index = cm_id_priv->alt_av.pkey_index;
-			qp_attr->alt_timeout =
-				cm_id_priv->alt_av.packet_life_time + 1;
+			qp_attr->alt_timeout = cm_id_priv->alt_av.timeout;
 			qp_attr->alt_ah_attr = cm_id_priv->alt_av.ah_attr;
 			qp_attr->path_mig_state = IB_MIG_REARM;
 		}
@@ -3343,6 +3375,16 @@ int ib_cm_init_qp_attr(struct ib_cm_id *cm_id,
 }
 EXPORT_SYMBOL(ib_cm_init_qp_attr);
 
+void cm_get_ack_delay(struct cm_device *cm_dev)
+{
+	struct ib_device_attr attr;
+
+	if (ib_query_device(cm_dev->device, &attr))
+		cm_dev->ack_delay = 0; /* acks will rely on packet life time */
+	else
+		cm_dev->ack_delay = attr.local_ca_ack_delay;
+}
+
 static void cm_add_one(struct ib_device *device)
 {
 	struct cm_device *cm_dev;
@@ -3367,6 +3409,7 @@ static void cm_add_one(struct ib_device *device)
 		return;
 
 	cm_dev->device = device;
+	cm_get_ack_delay(cm_dev);
 
 	set_bit(IB_MGMT_METHOD_SEND, reg_req.method_mask);
 	for (i = 1; i <= device->phys_port_cnt; i++) {