Re: [PATCH v5 5/5] PCI: endpoint: pci-epf-vntb: manage ntb_dev lifetime and fix vpci bus teardown

On Thu, Feb 26, 2026 at 05:41:42PM +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.
> 
> Reviewed-by: Frank Li <[email protected]>
> Signed-off-by: Koichiro Den <[email protected]>
> ---
> Changes since v4:
>   - Adjusted context due to commit:
>     dc693d606644 ("PCI: endpoint: pci-epf-vntb: Add MSI doorbell support")
> 
>  drivers/pci/endpoint/functions/pci-epf-vntb.c | 53 ++++++++++++++-----
>  1 file changed, 40 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> index f353e9a57194..41a2f42e8a39 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> @@ -120,7 +120,7 @@ struct epf_ntb_ctrl {
>  } __packed;
>  
>  struct epf_ntb {
> -	struct ntb_dev ntb;
> +	struct ntb_dev *ntb;
>  	struct pci_epf *epf;
>  	struct config_group group;
>  
> @@ -147,10 +147,16 @@ 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)

Nit: No need of 'inline' keyword in a .c file.

- Mani

> +{
> +	return (struct epf_ntb *)ntb->pdev->sysdata;
> +}
>  
>  static struct pci_epf_header epf_ntb_header = {
>  	.vendorid	= PCI_ANY_ID,
> @@ -176,7 +182,7 @@ 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;
>  }
>  
> @@ -264,7 +270,7 @@ static void epf_ntb_cmd_handler(struct work_struct *work)
>  	for (i = 1; i < ntb->db_count && !ntb->msi_doorbell; i++) {
>  		if (ntb->epf_db[i]) {
>  			atomic64_or(1 << (i - 1), &ntb->db);
> -			ntb_db_event(&ntb->ntb, i);
> +			ntb_db_event(ntb->ntb, i);
>  			ntb->epf_db[i] = 0;
>  		}
>  	}
> @@ -333,7 +339,7 @@ static irqreturn_t epf_ntb_doorbell_handler(int irq, void *data)
>  	for (i = 1; i < ntb->db_count; i++)
>  		if (irq == ntb->epf->db_msg[i].virq) {
>  			atomic64_or(1 << (i - 1), &ntb->db);
> -			ntb_db_event(&ntb->ntb, i);
> +			ntb_db_event(ntb->ntb, i);
>  		}
>  
>  	return IRQ_HANDLED;
> @@ -1237,6 +1243,7 @@ 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);
>  
> @@ -1281,7 +1288,7 @@ 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;
> @@ -1381,7 +1388,7 @@ 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;
>  }
> @@ -1468,9 +1475,12 @@ 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) {
> @@ -1478,7 +1488,7 @@ 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;
> @@ -1488,6 +1498,17 @@ 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),
> @@ -1499,6 +1520,7 @@ 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 ====================*/
> @@ -1581,10 +1603,15 @@ 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
> -- 
> 2.51.0
> 

-- 
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