linux-kernel - Re: [PATCH v2 4/6] PCI: endpoint: pci-epf-ntb: Remove duplicate resource teardown

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Message-ID: <aQJFd8Btdh1EY0Qz@lizhi-Precision-Tower-5810>
Date: Wed, 29 Oct 2025 12:48:55 -0400
From: Frank Li <Frank.li@....com>
To: Koichiro Den <den@...inux.co.jp>
Cc: ntb@...ts.linux.dev, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, jdmason@...zu.us,
	dave.jiang@...el.com, allenbh@...il.com, mani@...nel.org,
	kwilczynski@...nel.org, kishon@...nel.org, bhelgaas@...gle.com,
	jbrunet@...libre.com, lpieralisi@...nel.org, yebin10@...wei.com,
	geert+renesas@...der.be, arnd@...db.de
Subject: Re: [PATCH v2 4/6] PCI: endpoint: pci-epf-ntb: Remove duplicate
 resource teardown

On Wed, Oct 29, 2025 at 05:03:19PM +0900, Koichiro Den wrote:
> epf_ntb_epc_destroy() duplicates the teardown that the caller is
> supposed to do later. This leads to an oops when .allow_link fails or
> when .drop_link is performed. Remove the helper.
>
> Also drop pci_epc_put(). EPC device refcounting is tied to configfs EPC
> group lifetime, and pci_epc_put() in the .drop_link path is sufficient.
>
> Cc: <stable@...r.kernel.org>
> Fixes: 8b821cf76150 ("PCI: endpoint: Add EP function driver to provide NTB functionality")
> Signed-off-by: Koichiro Den <den@...inux.co.jp>

Reviewed-by: Frank Li <Frank.Li@....com>

> ---
>  drivers/pci/endpoint/functions/pci-epf-ntb.c | 56 +-------------------
>  1 file changed, 2 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-ntb.c b/drivers/pci/endpoint/functions/pci-epf-ntb.c
> index e01a98e74d21..7702ebb81d99 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-ntb.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-ntb.c
> @@ -1494,47 +1494,6 @@ static int epf_ntb_db_mw_bar_init(struct epf_ntb *ntb,
>  	return ret;
>  }
>
> -/**
> - * epf_ntb_epc_destroy_interface() - Cleanup NTB EPC interface
> - * @ntb: NTB device that facilitates communication between HOST1 and HOST2
> - * @type: PRIMARY interface or SECONDARY interface
> - *
> - * Unbind NTB function device from EPC and relinquish reference to pci_epc
> - * for each of the interface.
> - */
> -static void epf_ntb_epc_destroy_interface(struct epf_ntb *ntb,
> -					  enum pci_epc_interface_type type)
> -{
> -	struct epf_ntb_epc *ntb_epc;
> -	struct pci_epc *epc;
> -	struct pci_epf *epf;
> -
> -	if (type < 0)
> -		return;
> -
> -	epf = ntb->epf;
> -	ntb_epc = ntb->epc[type];
> -	if (!ntb_epc)
> -		return;
> -	epc = ntb_epc->epc;
> -	pci_epc_remove_epf(epc, epf, type);
> -	pci_epc_put(epc);
> -}
> -
> -/**
> - * epf_ntb_epc_destroy() - Cleanup NTB EPC interface
> - * @ntb: NTB device that facilitates communication between HOST1 and HOST2
> - *
> - * Wrapper for epf_ntb_epc_destroy_interface() to cleanup all the NTB interfaces
> - */
> -static void epf_ntb_epc_destroy(struct epf_ntb *ntb)
> -{
> -	enum pci_epc_interface_type type;
> -
> -	for (type = PRIMARY_INTERFACE; type <= SECONDARY_INTERFACE; type++)
> -		epf_ntb_epc_destroy_interface(ntb, type);
> -}
> -
>  /**
>   * epf_ntb_epc_create_interface() - Create and initialize NTB EPC interface
>   * @ntb: NTB device that facilitates communication between HOST1 and HOST2
> @@ -1614,15 +1573,8 @@ static int epf_ntb_epc_create(struct epf_ntb *ntb)
>
>  	ret = epf_ntb_epc_create_interface(ntb, epf->sec_epc,
>  					   SECONDARY_INTERFACE);
> -	if (ret) {
> +	if (ret)
>  		dev_err(dev, "SECONDARY intf: Fail to create NTB EPC\n");
> -		goto err_epc_create;
> -	}
> -
> -	return 0;
> -
> -err_epc_create:
> -	epf_ntb_epc_destroy_interface(ntb, PRIMARY_INTERFACE);
>
>  	return ret;
>  }
> @@ -1887,7 +1839,7 @@ static int epf_ntb_bind(struct pci_epf *epf)
>  	ret = epf_ntb_init_epc_bar(ntb);
>  	if (ret) {
>  		dev_err(dev, "Failed to create NTB EPC\n");
> -		goto err_bar_init;
> +		return ret;
>  	}
>
>  	ret = epf_ntb_config_spad_bar_alloc_interface(ntb);
> @@ -1909,9 +1861,6 @@ static int epf_ntb_bind(struct pci_epf *epf)
>  err_bar_alloc:
>  	epf_ntb_config_spad_bar_free(ntb);
>
> -err_bar_init:
> -	epf_ntb_epc_destroy(ntb);
> -
>  	return ret;
>  }
>
> @@ -1927,7 +1876,6 @@ static void epf_ntb_unbind(struct pci_epf *epf)
>
>  	epf_ntb_epc_cleanup(ntb);
>  	epf_ntb_config_spad_bar_free(ntb);
> -	epf_ntb_epc_destroy(ntb);
>  }
>
>  #define EPF_NTB_R(_name)						\
> --
> 2.48.1
>