[PATCH 12/12] IB/srp: Make CM timeout dependent on subnet timeout

[Bart Van Assche <bart.vanassche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>]

In large networks the subnet timeout may have been set to a value
above 20. In small networks it can be safe to reduce the subnet
timeout below 20. The CM timeout should be proportional to the
subnet timeout. Hence make the CM timeout dependent on the subnet
timeout. Since the default subnet timeout used by OpenSM is 18
this patch does not change the CM timeout if the default OpenSM
subnet timeout is used.

Signed-off-by: Bart Van Assche <bart.vanassche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>
Cc: Sagi Grimberg <sagig-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Cc: Sebastian Parschauer <sebastian.riemer-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
---
 drivers/infiniband/ulp/srp/ib_srp.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 27d3a64..a18a2ae 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -704,6 +704,19 @@ static int srp_lookup_path(struct srp_rdma_ch *ch)
 	return ch->status;
 }
 
+static u8 srp_get_subnet_timeout(struct srp_host *host)
+{
+	struct ib_port_attr attr;
+	int ret;
+	u8 subnet_timeout = 18;
+
+	ret = ib_query_port(host->srp_dev->dev, host->port, &attr);
+	if (ret == 0)
+		subnet_timeout = attr.subnet_timeout;
+
+	return subnet_timeout;
+}
+
 static int srp_send_req(struct srp_rdma_ch *ch, bool multich)
 {
 	struct srp_target_port *target = ch->target;
@@ -711,8 +724,11 @@ static int srp_send_req(struct srp_rdma_ch *ch, bool multich)
 		struct ib_cm_req_param param;
 		struct srp_login_req   priv;
 	} *req = NULL;
+	u8 subnet_timeout;
 	int status;
 
+	subnet_timeout = srp_get_subnet_timeout(target->srp_host);
+
 	req = kzalloc(sizeof *req, GFP_KERNEL);
 	if (!req)
 		return -ENOMEM;
@@ -734,8 +750,8 @@ static int srp_send_req(struct srp_rdma_ch *ch, bool multich)
 	 * module parameters if anyone cared about setting them.
 	 */
 	req->param.responder_resources	      = 4;
-	req->param.remote_cm_response_timeout = 20;
-	req->param.local_cm_response_timeout  = 20;
+	req->param.remote_cm_response_timeout = subnet_timeout + 2;
+	req->param.local_cm_response_timeout  = subnet_timeout + 2;
 	req->param.retry_count                = target->tl_retry_count;
 	req->param.rnr_retry_count 	      = 7;
 	req->param.max_cm_retries 	      = 15;
-- 
2.1.4

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