[PATCH v2] nvme_fc: retry initial controller connections 3 times

[jsmart2021@gmail.com (James Smart)]

Currently, if a frame is lost of command fails as part of initial
association create for a new controller, the new controller connection
request will immediately fail.

Add in an immediate 3 retry loop before giving up.

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

---
v2:
  Add additional comment information on why the retries. The comment
  should sufficiently explain the background.
  Note: rdma, in most cases, if initial connections or commands failed,
  would also fail on first connect attempt.
---
 drivers/nvme/host/fc.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 1075488a81d6..18e036c6833b 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -2790,7 +2790,7 @@ nvme_fc_init_ctrl(struct device *dev, struct nvmf_ctrl_options *opts,
 {
 	struct nvme_fc_ctrl *ctrl;
 	unsigned long flags;
-	int ret, idx;
+	int ret, idx, retry;
 
 	if (!(rport->remoteport.port_role &
 	    (FC_PORT_ROLE_NVME_DISCOVERY | FC_PORT_ROLE_NVME_TARGET))) {
@@ -2882,9 +2882,37 @@ nvme_fc_init_ctrl(struct device *dev, struct nvmf_ctrl_options *opts,
 	list_add_tail(&ctrl->ctrl_list, &rport->ctrl_list);
 	spin_unlock_irqrestore(&rport->lock, flags);
 
-	ret = nvme_fc_create_association(ctrl);
+	/*
+	 * It's possible that transactions used to create the association
+	 * may fail. Examples: CreateAssociation LS or CreateIOConnection
+	 * LS gets dropped/corrupted/fails; or a frame gets dropped or a
+	 * command times out for one of the actions to init the controller
+	 * (Connect, Get/Set_Property, Set_Features, etc). Many of these
+	 * transport errors (frame drop, LS failure) inherently must kill
+	 * the association. The transport is coded so that any command used
+	 * to create the association (prior to a LIVE state transition
+	 * while NEW or RECONNECTING) will fail if it completes in error or
+	 * times out.
+	 *
+	 * As such: as the connect request was mostly likely due to a
+	 * udev event that discovered the remote port, meaning there is
+	 * not an admin or script there to restart if the connect
+	 * request fails, retry the initial connection creation up to
+	 * three times before giving up and declaring failure.
+	 */
+	for (retry = 0; retry < 3; retry++) {
+		ret = nvme_fc_create_association(ctrl);
+		if (!ret)
+			break;
+	}
+
 	if (ret) {
+		/* couldn't schedule retry - fail out */
+		dev_err(ctrl->ctrl.device,
+			"NVME-FC{%d}: Connect retry failed\n", ctrl->cnum);
+
 		ctrl->ctrl.opts = NULL;
+
 		/* initiate nvme ctrl ref counting teardown */
 		nvme_uninit_ctrl(&ctrl->ctrl);
 		nvme_put_ctrl(&ctrl->ctrl);
-- 
2.13.1