[PATCH v3 3/5] nvme_fc: add a dev_loss_tmo field to the remoteport

[jsmart2021@gmail.com (James Smart)]

Add a dev_loss_tmo value, paralleling the SCSI FC transport, for device
connectivity loss.

The transport initializes the value in the nvme_fc_register_remoteport()
call. If the value is not set, a default of 60s is set.

Add a new routine to the api, nvme_fc_set_remoteport_devloss() routine,
which allows the lldd to dynamically update the value on an existing
remoteport.

Signed-off-by: James Smart <james.smart at broadcom.com>

---
v3:
 Removed the expected reconnect time and min devloss defines. They
 were not that meaningful.
 Incorporated the new nvme_fc_set_remoteport_devloss() routine
 which was in a different patch in v2. New routine no longer
 touches controllers. It only modifies the remoteport.
---
 drivers/nvme/host/fc.c         | 31 +++++++++++++++++++++++++++++++
 include/linux/nvme-fc-driver.h | 11 +++++++++--
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 5afb518c39ad..3ac49e670c38 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -45,6 +45,8 @@ enum nvme_fc_queue_flags {
 
 #define NVMEFC_QUEUE_DELAY	3		/* ms units */
 
+#define NVME_FC_DEFAULT_DEV_LOSS_TMO	60	/* seconds */
+
 struct nvme_fc_queue {
 	struct nvme_fc_ctrl	*ctrl;
 	struct device		*dev;
@@ -587,6 +589,11 @@ nvme_fc_register_remoteport(struct nvme_fc_local_port *localport,
 	newrec->remoteport.port_id = pinfo->port_id;
 	newrec->remoteport.port_state = FC_OBJSTATE_ONLINE;
 	newrec->remoteport.port_num = idx;
+	/* a registration value of dev_loss_tmo=0 results in the default */
+	if (pinfo->dev_loss_tmo)
+		newrec->remoteport.dev_loss_tmo = pinfo->dev_loss_tmo;
+	else
+		newrec->remoteport.dev_loss_tmo = NVME_FC_DEFAULT_DEV_LOSS_TMO;
 
 	spin_lock_irqsave(&nvme_fc_lock, flags);
 	list_add_tail(&newrec->endp_list, &lport->endp_list);
@@ -690,6 +697,30 @@ nvme_fc_rescan_remoteport(struct nvme_fc_remote_port *remoteport)
 }
 EXPORT_SYMBOL_GPL(nvme_fc_rescan_remoteport);
 
+int
+nvme_fc_set_remoteport_devloss(struct nvme_fc_remote_port *portptr,
+			u32 dev_loss_tmo)
+{
+	struct nvme_fc_rport *rport = remoteport_to_rport(portptr);
+	struct nvme_fc_ctrl *ctrl;
+	unsigned long flags;
+
+	spin_lock_irqsave(&rport->lock, flags);
+
+	if (portptr->port_state != FC_OBJSTATE_ONLINE) {
+		spin_unlock_irqrestore(&rport->lock, flags);
+		return -EINVAL;
+	}
+
+	/* a dev_loss_tmo of 0 (immediate) is allowed to be set */
+	rport->remoteport.dev_loss_tmo = dev_loss_tmo;
+
+	spin_unlock_irqrestore(&rport->lock, flags);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nvme_fc_set_remoteport_devloss);
+
 
 /* *********************** FC-NVME DMA Handling **************************** */
 
diff --git a/include/linux/nvme-fc-driver.h b/include/linux/nvme-fc-driver.h
index 4ea03b9a5c8c..3de268bf86bf 100644
--- a/include/linux/nvme-fc-driver.h
+++ b/include/linux/nvme-fc-driver.h
@@ -40,6 +40,8 @@
  * @node_name: FC WWNN for the port
  * @port_name: FC WWPN for the port
  * @port_role: What NVME roles are supported (see FC_PORT_ROLE_xxx)
+ * @dev_loss_tmo: maximum delay for reconnects to an association on
+ *             this device. Used only on a remoteport.
  *
  * Initialization values for dynamic port fields:
  * @port_id:      FC N_Port_ID currently assigned the port. Upper 8 bits must
@@ -50,6 +52,7 @@ struct nvme_fc_port_info {
 	u64			port_name;
 	u32			port_role;
 	u32			port_id;
+	u32			dev_loss_tmo;
 };
 
 
@@ -202,6 +205,9 @@ enum nvme_fc_obj_state {
  *             The length of the buffer corresponds to the local_priv_sz
  *             value specified in the nvme_fc_port_template supplied by
  *             the LLDD.
+ * @dev_loss_tmo: maximum delay for reconnects to an association on
+ *             this device. To modify, lldd must call
+ *             nvme_fc_set_remoteport_devloss().
  *
  * Fields with dynamic values. Values may change base on link state. LLDD
  * may reference fields directly to change them. Initialized by the
@@ -259,10 +265,9 @@ struct nvme_fc_remote_port {
 	u32 port_role;
 	u64 node_name;
 	u64 port_name;
-
 	struct nvme_fc_local_port *localport;
-
 	void *private;
+	u32 dev_loss_tmo;
 
 	/* dynamic fields */
 	u32 port_id;
@@ -448,6 +453,8 @@ int nvme_fc_unregister_remoteport(struct nvme_fc_remote_port *remoteport);
 
 void nvme_fc_rescan_remoteport(struct nvme_fc_remote_port *remoteport);
 
+int nvme_fc_set_remoteport_devloss(struct nvme_fc_remote_port *remoteport,
+			u32 dev_loss_tmo);
 
 
 /*
-- 
2.13.1