[PATCH 2/7] nvmet-fc: use per-target workqueue when removing associations

[Hannes Reinecke]

When removing target ports all outstanding associations need to be
terminated / cleaned up. As this involves several exchanges on the
wire a synchronization point is required to establish when these
exchanges have ran their course and it's safe to delete the association.
So add a per-target workqueue and flush this workqueue to ensure
the association can really be deleted.

Signed-off-by: Hannes Reinecke <hare at suse.de>
---
 drivers/nvme/target/fc.c | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
index 04ec0076ae59..63f5deb3b68a 100644
--- a/drivers/nvme/target/fc.c
+++ b/drivers/nvme/target/fc.c
@@ -99,6 +99,7 @@ struct nvmet_fc_tgtport {
 	struct list_head		tgt_list; /* nvmet_fc_target_list */
 	struct device			*dev;	/* dev for dma mapping */
 	struct nvmet_fc_target_template	*ops;
+	struct workqueue_struct		*work_q;
 
 	struct nvmet_fc_ls_iod		*iod;
 	spinlock_t			lock;
@@ -1403,10 +1404,17 @@ nvmet_fc_register_targetport(struct nvmet_fc_port_info *pinfo,
 	ida_init(&newrec->assoc_cnt);
 	newrec->max_sg_cnt = template->max_sgl_segments;
 
+	newrec->work_q = alloc_workqueue("ntfc%d", 0, 0,
+					 newrec->fc_target_port.port_num);
+	if (!newrec->work_q) {
+		ret = -ENOMEM;
+		goto out_free_newrec;
+	}
+
 	ret = nvmet_fc_alloc_ls_iodlist(newrec);
 	if (ret) {
 		ret = -ENOMEM;
-		goto out_free_newrec;
+		goto out_free_workq;
 	}
 
 	nvmet_fc_portentry_rebind_tgt(newrec);
@@ -1418,6 +1426,8 @@ nvmet_fc_register_targetport(struct nvmet_fc_port_info *pinfo,
 	*portptr = &newrec->fc_target_port;
 	return 0;
 
+out_free_workq:
+	destroy_workqueue(newrec->work_q);
 out_free_newrec:
 	put_device(dev);
 out_ida_put:
@@ -1443,6 +1453,8 @@ nvmet_fc_free_tgtport(struct kref *ref)
 	list_del(&tgtport->tgt_list);
 	spin_unlock_irqrestore(&nvmet_fc_tgtlock, flags);
 
+	destroy_workqueue(tgtport->work_q);
+
 	nvmet_fc_free_ls_iodlist(tgtport);
 
 	/* let the LLDD know we've finished tearing it down */
@@ -1481,11 +1493,13 @@ __nvmet_fc_free_assocs(struct nvmet_fc_tgtport *tgtport)
 				&tgtport->assoc_list, a_list) {
 		if (!nvmet_fc_tgt_a_get(assoc))
 			continue;
-		if (!schedule_work(&assoc->del_work))
+		if (!queue_work(tgtport->work_q, &assoc->del_work))
 			/* already deleting - release local reference */
 			nvmet_fc_tgt_a_put(assoc);
 	}
 	spin_unlock_irqrestore(&tgtport->lock, flags);
+
+	flush_workqueue(tgtport->work_q);
 }
 
 /**
@@ -1536,12 +1550,14 @@ nvmet_fc_invalidate_host(struct nvmet_fc_target_port *target_port,
 			continue;
 		assoc->hostport->invalid = 1;
 		noassoc = false;
-		if (!schedule_work(&assoc->del_work))
+		if (!queue_work(tgtport->work_q, &assoc->del_work))
 			/* already deleting - release local reference */
 			nvmet_fc_tgt_a_put(assoc);
 	}
 	spin_unlock_irqrestore(&tgtport->lock, flags);
 
+	flush_workqueue(tgtport->work_q);
+
 	/* if there's nothing to wait for - call the callback */
 	if (noassoc && tgtport->ops->host_release)
 		tgtport->ops->host_release(hosthandle);
@@ -1579,14 +1595,15 @@ nvmet_fc_delete_ctrl(struct nvmet_ctrl *ctrl)
 		}
 		spin_unlock_irqrestore(&tgtport->lock, flags);
 
-		nvmet_fc_tgtport_put(tgtport);
-
 		if (found_ctrl) {
-			if (!schedule_work(&assoc->del_work))
+			if (!queue_work(tgtport->work_q, &assoc->del_work))
 				/* already deleting - release local reference */
 				nvmet_fc_tgt_a_put(assoc);
+			flush_workqueue(tgtport->work_q);
+			nvmet_fc_tgtport_put(tgtport);
 			return;
 		}
+		nvmet_fc_tgtport_put(tgtport);
 
 		spin_lock_irqsave(&nvmet_fc_tgtlock, flags);
 	}
-- 
2.16.4