Currently ntb_dev is embedded in epf_ntb, while configfs allows starting
or stopping controller and linking or unlinking functions as you want.
In fact, re-linking and re-starting is not possible with the embedded
design and leads to oopses.

Allocate ntb_dev with devm and add a .remove callback to the pci driver
that calls ntb_unregister_device(). This allows a fresh device to be
created on the next .bind call.

With these changes, the controller can now be stopped, a function
unlinked, configfs settings updated, and the controller re-linked and
restarted without rebooting the endpoint, as long as the underlying
pci_epc_ops .stop() operation is non-destructive, and .start() can
restore normal operations.

Signed-off-by: Koichiro Den <den@valinux.co.jp>
---
 drivers/pci/endpoint/functions/pci-epf-vntb.c | 52 ++++++++++++++-----
 1 file changed, 39 insertions(+), 13 deletions(-)

diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
index af0651c03b20..3059ed85a955 100644
--- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
@@ -118,7 +118,7 @@ struct epf_ntb_ctrl {
 } __packed;
 
 struct epf_ntb {
-	struct ntb_dev ntb;
+	struct ntb_dev *ntb;
 	struct pci_epf *epf;
 	struct config_group group;
 
@@ -144,10 +144,16 @@ struct epf_ntb {
 	void __iomem *vpci_mw_addr[MAX_MW];
 
 	struct delayed_work cmd_handler;
+
+	struct pci_bus *vpci_bus;
 };
 
 #define to_epf_ntb(epf_group) container_of((epf_group), struct epf_ntb, group)
-#define ntb_ndev(__ntb) container_of(__ntb, struct epf_ntb, ntb)
+
+static inline struct epf_ntb *ntb_ndev(struct ntb_dev *ntb)
+{
+	return (struct epf_ntb *)ntb->pdev->sysdata;
+}
 
 static struct pci_epf_header epf_ntb_header = {
 	.vendorid	= PCI_ANY_ID,
@@ -173,7 +179,7 @@ static int epf_ntb_link_up(struct epf_ntb *ntb, bool link_up)
 	else
 		ntb->reg->link_status &= ~LINK_STATUS_UP;
 
-	ntb_link_event(&ntb->ntb);
+	ntb_link_event(ntb->ntb);
 	return 0;
 }
 
@@ -261,7 +267,7 @@ static void epf_ntb_cmd_handler(struct work_struct *work)
 	for (i = 1; i < ntb->db_count; i++) {
 		if (ntb->epf_db[i]) {
 			ntb->db |= 1 << (i - 1);
-			ntb_db_event(&ntb->ntb, i);
+			ntb_db_event(ntb->ntb, i);
 			ntb->epf_db[i] = 0;
 		}
 	}
@@ -1097,7 +1103,6 @@ static int vpci_scan_bus(void *sysdata)
 {
 	struct pci_bus *vpci_bus;
 	struct epf_ntb *ndev = sysdata;
-
 	LIST_HEAD(resources);
 	static struct resource busn_res = {
 		.start = 0,
@@ -1115,6 +1120,7 @@ static int vpci_scan_bus(void *sysdata)
 		pr_err("create pci bus failed\n");
 		return -EINVAL;
 	}
+	ndev->vpci_bus = vpci_bus;
 
 	pci_bus_add_devices(vpci_bus);
 
@@ -1159,7 +1165,7 @@ static int vntb_epf_mw_set_trans(struct ntb_dev *ndev, int pidx, int idx,
 	int ret;
 	struct device *dev;
 
-	dev = &ntb->ntb.dev;
+	dev = &ntb->ntb->dev;
 	barno = ntb->epf_ntb_bar[BAR_MW1 + idx];
 	epf_bar = &ntb->epf->bar[barno];
 	epf_bar->phys_addr = addr;
@@ -1259,7 +1265,7 @@ static int vntb_epf_peer_db_set(struct ntb_dev *ndev, u64 db_bits)
 	ret = pci_epc_raise_irq(ntb->epf->epc, func_no, vfunc_no,
 				PCI_IRQ_MSI, interrupt_num + 1);
 	if (ret)
-		dev_err(&ntb->ntb.dev, "Failed to raise IRQ\n");
+		dev_err(&ntb->ntb->dev, "Failed to raise IRQ\n");
 
 	return ret;
 }
@@ -1346,9 +1352,12 @@ static int pci_vntb_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	struct epf_ntb *ndev = (struct epf_ntb *)pdev->sysdata;
 	struct device *dev = &pdev->dev;
 
-	ndev->ntb.pdev = pdev;
-	ndev->ntb.topo = NTB_TOPO_NONE;
-	ndev->ntb.ops =  &vntb_epf_ops;
+	ndev->ntb = devm_kzalloc(dev, sizeof(*ndev->ntb), GFP_KERNEL);
+	if (!ndev->ntb)
+		return -ENOMEM;
+	ndev->ntb->pdev = pdev;
+	ndev->ntb->topo = NTB_TOPO_NONE;
+	ndev->ntb->ops = &vntb_epf_ops;
 
 	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
 	if (ret) {
@@ -1356,7 +1365,7 @@ static int pci_vntb_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		return ret;
 	}
 
-	ret = ntb_register_device(&ndev->ntb);
+	ret = ntb_register_device(ndev->ntb);
 	if (ret) {
 		dev_err(dev, "Failed to register NTB device\n");
 		return ret;
@@ -1366,6 +1375,17 @@ static int pci_vntb_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	return 0;
 }
 
+static void pci_vntb_remove(struct pci_dev *pdev)
+{
+	struct epf_ntb *ndev = (struct epf_ntb *)pdev->sysdata;
+
+	if (!ndev || !ndev->ntb)
+		return;
+
+	ntb_unregister_device(ndev->ntb);
+	ndev->ntb = NULL;
+}
+
 static struct pci_device_id pci_vntb_table[] = {
 	{
 		PCI_DEVICE(0xffff, 0xffff),
@@ -1377,6 +1397,7 @@ static struct pci_driver vntb_pci_driver = {
 	.name           = "pci-vntb",
 	.id_table       = pci_vntb_table,
 	.probe          = pci_vntb_probe,
+	.remove         = pci_vntb_remove,
 };
 
 /* ============ PCIe EPF Driver Bind ====================*/
@@ -1459,10 +1480,15 @@ static void epf_ntb_unbind(struct pci_epf *epf)
 {
 	struct epf_ntb *ntb = epf_get_drvdata(epf);
 
+	pci_unregister_driver(&vntb_pci_driver);
+
+	pci_lock_rescan_remove();
+	pci_stop_root_bus(ntb->vpci_bus);
+	pci_remove_root_bus(ntb->vpci_bus);
+	pci_unlock_rescan_remove();
+
 	epf_ntb_epc_cleanup(ntb);
 	epf_ntb_config_spad_bar_free(ntb);
-
-	pci_unregister_driver(&vntb_pci_driver);
 }
 
 // EPF driver probe
-- 
2.48.1

On Mon, Dec 01, 2025 at 12:11:00AM +0900, Koichiro Den wrote:
> Currently ntb_dev is embedded in epf_ntb, while configfs allows starting
> or stopping controller and linking or unlinking functions as you want.
> In fact, re-linking and re-starting is not possible with the embedded
> design and leads to oopses.
>
> Allocate ntb_dev with devm and add a .remove callback to the pci driver
> that calls ntb_unregister_device(). This allows a fresh device to be
> created on the next .bind call.
>
> With these changes, the controller can now be stopped, a function
> unlinked, configfs settings updated, and the controller re-linked and
> restarted without rebooting the endpoint, as long as the underlying
> pci_epc_ops .stop() operation is non-destructive, and .start() can
> restore normal operations.
>
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> ---
>  drivers/pci/endpoint/functions/pci-epf-vntb.c | 52 ++++++++++++++-----
>  1 file changed, 39 insertions(+), 13 deletions(-)
...
> @@ -1097,7 +1103,6 @@ static int vpci_scan_bus(void *sysdata)
>  {
>  	struct pci_bus *vpci_bus;
>  	struct epf_ntb *ndev = sysdata;
> -

Unneccsary change here.

Frank Li

>  	LIST_HEAD(resources);
>  	static struct resource busn_res = {
>  		.start = 0,
> @@ -1115,6 +1120,7 @@ static int vpci_scan_bus(void *sysdata)
>  		pr_err("create pci bus failed\n");
>  		return -EINVAL;
>  	}
> +	ndev->vpci_bus = vpci_bus;
>
>  	pci_bus_add_devices(vpci_bus);
>
> @@ -1159,7 +1165,7 @@ static int vntb_epf_mw_set_trans(struct ntb_dev *ndev, int pidx, int idx,
>  	int ret;
>  	struct device *dev;
>
> -	dev = &ntb->ntb.dev;
> +	dev = &ntb->ntb->dev;
>  	barno = ntb->epf_ntb_bar[BAR_MW1 + idx];
>  	epf_bar = &ntb->epf->bar[barno];
>  	epf_bar->phys_addr = addr;
> @@ -1259,7 +1265,7 @@ static int vntb_epf_peer_db_set(struct ntb_dev *ndev, u64 db_bits)
>  	ret = pci_epc_raise_irq(ntb->epf->epc, func_no, vfunc_no,
>  				PCI_IRQ_MSI, interrupt_num + 1);
>  	if (ret)
> -		dev_err(&ntb->ntb.dev, "Failed to raise IRQ\n");
> +		dev_err(&ntb->ntb->dev, "Failed to raise IRQ\n");
>
>  	return ret;
>  }
> @@ -1346,9 +1352,12 @@ static int pci_vntb_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	struct epf_ntb *ndev = (struct epf_ntb *)pdev->sysdata;
>  	struct device *dev = &pdev->dev;
>
> -	ndev->ntb.pdev = pdev;
> -	ndev->ntb.topo = NTB_TOPO_NONE;
> -	ndev->ntb.ops =  &vntb_epf_ops;
> +	ndev->ntb = devm_kzalloc(dev, sizeof(*ndev->ntb), GFP_KERNEL);
> +	if (!ndev->ntb)
> +		return -ENOMEM;
> +	ndev->ntb->pdev = pdev;
> +	ndev->ntb->topo = NTB_TOPO_NONE;
> +	ndev->ntb->ops = &vntb_epf_ops;
>
>  	ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
>  	if (ret) {
> @@ -1356,7 +1365,7 @@ static int pci_vntb_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  		return ret;
>  	}
>
> -	ret = ntb_register_device(&ndev->ntb);
> +	ret = ntb_register_device(ndev->ntb);
>  	if (ret) {
>  		dev_err(dev, "Failed to register NTB device\n");
>  		return ret;
> @@ -1366,6 +1375,17 @@ static int pci_vntb_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	return 0;
>  }
>
> +static void pci_vntb_remove(struct pci_dev *pdev)
> +{
> +	struct epf_ntb *ndev = (struct epf_ntb *)pdev->sysdata;
> +
> +	if (!ndev || !ndev->ntb)
> +		return;
> +
> +	ntb_unregister_device(ndev->ntb);
> +	ndev->ntb = NULL;
> +}
> +
>  static struct pci_device_id pci_vntb_table[] = {
>  	{
>  		PCI_DEVICE(0xffff, 0xffff),
> @@ -1377,6 +1397,7 @@ static struct pci_driver vntb_pci_driver = {
>  	.name           = "pci-vntb",
>  	.id_table       = pci_vntb_table,
>  	.probe          = pci_vntb_probe,
> +	.remove         = pci_vntb_remove,
>  };
>
>  /* ============ PCIe EPF Driver Bind ====================*/
> @@ -1459,10 +1480,15 @@ static void epf_ntb_unbind(struct pci_epf *epf)
>  {
>  	struct epf_ntb *ntb = epf_get_drvdata(epf);
>
> +	pci_unregister_driver(&vntb_pci_driver);
> +
> +	pci_lock_rescan_remove();
> +	pci_stop_root_bus(ntb->vpci_bus);
> +	pci_remove_root_bus(ntb->vpci_bus);
> +	pci_unlock_rescan_remove();
> +
>  	epf_ntb_epc_cleanup(ntb);
>  	epf_ntb_config_spad_bar_free(ntb);
> -
> -	pci_unregister_driver(&vntb_pci_driver);
>  }
>
>  // EPF driver probe
> --
> 2.48.1
>