[ofa-general] [RFC 2.6.24-rc] IB/srp: retry stale connections

[David Dillow]

When a host just goes away (crash, power loss, etc.) without tearing
down its IB connections, it can get stale connection errors when it
tries to reconnect the targets upon rebooting. Retrying the connection a
few times will prevent sysadmins from playing the "which disk(s) went
missing?" game.

Signed-off-by: David Dillow <dillowda at ornl.gov>
---
This would have made things slightly quicker when tracking down some of
the recent bugs, but it also helps quite a bit when you've got a large
number of targets hanging off a wedged server.

This applies on top of the logging patches for ib_srp.

 ib_srp.c |   53 +++++++++++++++++++++++++++++++++++++++++------------
 ib_srp.h |    1 +
 2 files changed, 42 insertions(+), 12 deletions(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 154ebb0..167b39c 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -204,6 +204,22 @@ out:
 	return ret;
 }
 
+static int srp_new_cm_id(struct srp_target_port *target)
+{
+	struct ib_cm_id *new_cm_id;
+
+	new_cm_id = ib_create_cm_id(target->srp_host->dev->dev,
+				    srp_cm_handler, target);
+	if (IS_ERR(new_cm_id))
+		return PTR_ERR(new_cm_id);
+
+	if (target->cm_id)
+		ib_destroy_cm_id(target->cm_id);
+	target->cm_id = new_cm_id;
+
+	return 0;
+}
+
 static int srp_create_target_ib(struct srp_target_port *target)
 {
 	struct ib_qp_init_attr *init_attr;
@@ -436,6 +452,7 @@ static void srp_remove_work(struct work_struct *work)
 
 static int srp_connect_target(struct srp_target_port *target)
 {
+	int retries = 3;
 	int ret;
 
 	ret = srp_lookup_path(target);
@@ -468,6 +485,21 @@ static int srp_connect_target(struct srp_target_port *target)
 		case SRP_DLID_REDIRECT:
 			break;
 
+		case SRP_STALE_CONN:
+			/* Our current CM id was stale, and is now in timewait.
+			 * Try to reconnect with a new one.
+			 */
+			if (!retries-- || srp_new_cm_id(target)) {
+				shost_printk(KERN_ERR, target->scsi_host, PFX
+					     "giving up on stale connection\n");
+				target->status = -ECONNRESET;
+				return target->status;
+			}
+
+			shost_printk(KERN_ERR, target->scsi_host, PFX
+				     "retrying stale connection\n");
+			break;
+
 		default:
 			return target->status;
 		}
@@ -507,7 +539,6 @@ static void srp_reset_req(struct srp_target_port *target, struct srp_request *re
 
 static int srp_reconnect_target(struct srp_target_port *target)
 {
-	struct ib_cm_id *new_cm_id;
 	struct ib_qp_attr qp_attr;
 	struct srp_request *req, *tmp;
 	struct ib_wc wc;
@@ -526,14 +557,9 @@ static int srp_reconnect_target(struct srp_target_port *target)
 	 * Now get a new local CM ID so that we avoid confusing the
 	 * target in case things are really fouled up.
 	 */
-	new_cm_id = ib_create_cm_id(target->srp_host->dev->dev,
-				    srp_cm_handler, target);
-	if (IS_ERR(new_cm_id)) {
-		ret = PTR_ERR(new_cm_id);
+	ret = srp_new_cm_id(target);
+	if (ret)
 		goto err;
-	}
-	ib_destroy_cm_id(target->cm_id);
-	target->cm_id = new_cm_id;
 
 	qp_attr.qp_state = IB_QPS_RESET;
 	ret = ib_modify_qp(target->qp, &qp_attr, IB_QP_STATE);
@@ -1166,6 +1192,11 @@ static void srp_cm_rej_handler(struct ib_cm_id *cm_id,
 		target->status = -ECONNRESET;
 		break;
 
+	case IB_CM_REJ_STALE_CONN:
+		shost_printk(KERN_WARNING, shost, "  REJ reason: stale connection\n");
+		target->status = SRP_STALE_CONN;
+		break;
+
 	default:
 		shost_printk(KERN_WARNING, shost, "  REJ reason 0x%x\n",
 			     event->param.rej_rcvd.reason);
@@ -1857,11 +1888,9 @@ static ssize_t srp_create_target(struct class_device *class_dev,
 	if (ret)
 		goto err;
 
-	target->cm_id = ib_create_cm_id(host->dev->dev, srp_cm_handler, target);
-	if (IS_ERR(target->cm_id)) {
-		ret = PTR_ERR(target->cm_id);
+	ret = srp_new_cm_id(target);
+	if (ret)
 		goto err_free;
-	}
 
 	target->qp_in_error = 0;
 	ret = srp_connect_target(target);
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index e3573e7..00cfd70 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -54,6 +54,7 @@ enum {
 
 	SRP_PORT_REDIRECT	= 1,
 	SRP_DLID_REDIRECT	= 2,
+	SRP_STALE_CONN		= 3,
 
 	SRP_MAX_LUN		= 512,
 	SRP_DEF_SG_TABLESIZE	= 12,