nvme_fcloop: disassocate local port structs

The current fcloop driver gets its lport structure from the private
area co-allocated with the fc_localport. All is fine except the
teardown path, which wants to wait on the completion, which is marked
complete by the delete_localport callback performed after
unregister_localport.  The issue is, the nvme_fc transport frees the
localport structure immediately after delete_localport is called,
meaning the original routine is trying to wait on a complete that
was just freed.

Change such that a lport struct is allocated coincident with the
addition and registration of a localport. The private area of the
localport now contains just a backpointer to the real lport struct.
Now, the completion can be waited for, and after completing, the
new structure can be kfree'd.
Signed-off-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/fcloop.c

@@ -204,6 +204,10 @@ struct fcloop_lport {
 	struct completion unreg_done;
 };
 
+struct fcloop_lport_priv {
+	struct fcloop_lport *lport;
+};
+
 struct fcloop_rport {
 	struct nvme_fc_remote_port *remoteport;
 	struct nvmet_fc_target_port *targetport;
@@ -659,7 +663,8 @@ fcloop_nport_get(struct fcloop_nport *nport)
 static void
 fcloop_localport_delete(struct nvme_fc_local_port *localport)
 {
-	struct fcloop_lport *lport = localport->private;
+	struct fcloop_lport_priv *lport_priv = localport->private;
+	struct fcloop_lport *lport = lport_priv->lport;
 
 	/* release any threads waiting for the unreg to complete */
 	complete(&lport->unreg_done);
@@ -699,7 +704,7 @@ static struct nvme_fc_port_template fctemplate = {
 	.max_dif_sgl_segments	= FCLOOP_SGL_SEGS,
 	.dma_boundary		= FCLOOP_DMABOUND_4G,
 	/* sizes of additional private data for data structures */
-	.local_priv_sz		= sizeof(struct fcloop_lport),
+	.local_priv_sz		= sizeof(struct fcloop_lport_priv),
 	.remote_priv_sz		= sizeof(struct fcloop_rport),
 	.lsrqst_priv_sz		= sizeof(struct fcloop_lsreq),
 	.fcprqst_priv_sz	= sizeof(struct fcloop_ini_fcpreq),
@@ -730,11 +735,17 @@ fcloop_create_local_port(struct device *dev, struct device_attribute *attr,
 	struct fcloop_ctrl_options *opts;
 	struct nvme_fc_local_port *localport;
 	struct fcloop_lport *lport;
-	int ret;
+	struct fcloop_lport_priv *lport_priv;
+	unsigned long flags;
+	int ret = -ENOMEM;
+
+	lport = kzalloc(sizeof(*lport), GFP_KERNEL);
+	if (!lport)
+		return -ENOMEM;
 
 	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
 	if (!opts)
-		return -ENOMEM;
+		goto out_free_lport;
 
 	ret = fcloop_parse_options(opts, buf);
 	if (ret)
@@ -754,23 +765,25 @@ fcloop_create_local_port(struct device *dev, struct device_attribute *attr,
 
 	ret = nvme_fc_register_localport(&pinfo, &fctemplate, NULL, &localport);
 	if (!ret) {
-		unsigned long flags;
-
 		/* success */
-		lport = localport->private;
+		lport_priv = localport->private;
+		lport_priv->lport = lport;
+
 		lport->localport = localport;
 		INIT_LIST_HEAD(&lport->lport_list);
 
 		spin_lock_irqsave(&fcloop_lock, flags);
 		list_add_tail(&lport->lport_list, &fcloop_lports);
 		spin_unlock_irqrestore(&fcloop_lock, flags);
-
-		/* mark all of the input buffer consumed */
-		ret = count;
 	}
 
 out_free_opts:
 	kfree(opts);
+out_free_lport:
+	/* free only if we're going to fail */
+	if (ret)
+		kfree(lport);
+
 	return ret ? ret : count;
 }
 
@@ -792,6 +805,8 @@ __wait_localport_unreg(struct fcloop_lport *lport)
 
 	wait_for_completion(&lport->unreg_done);
 
+	kfree(lport);
+
 	return ret;
 }