Re: [PATCH 1/4] PCI: endpoint: pci-epf-vntb: Fix MSI doorbell IRQ unwind

[Niklas Cassel <cassel@kernel.org>]

On Mon, Feb 16, 2026 at 12:09:11AM +0900, Koichiro Den wrote:
> epf_ntb_db_bar_init_msi_doorbell() requests ntb->db_count doorbell IRQs
> and then performs additional MSI doorbell setup that may still fail.
> The error path unwinds the requested IRQs, but it uses a loop variable
> that is reused later in the function. When a later step fails, the
> unwind can run with an unexpected index value and leave some IRQs
> requested.
> 
> Track the number of successfully requested IRQs separately and use that
> counter for the unwind so all previously requested IRQs are freed on
> failure.
> 
> Fixes: dc693d606644 ("PCI: endpoint: pci-epf-vntb: Add MSI doorbell support")
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> ---
>  drivers/pci/endpoint/functions/pci-epf-vntb.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> index 20a400e83439..20efa27325f1 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
> @@ -523,6 +523,7 @@ static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
>  					    enum pci_barno barno)
>  {
>  	struct pci_epf *epf = ntb->epf;
> +	unsigned int req;
>  	dma_addr_t low, high;
>  	struct msi_msg *msg;
>  	size_t sz;
> @@ -533,14 +534,14 @@ static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
>  	if (ret)
>  		return ret;
>  
> -	for (i = 0; i < ntb->db_count; i++) {
> -		ret = request_irq(epf->db_msg[i].virq, epf_ntb_doorbell_handler,
> +	for (req = 0; req < ntb->db_count; req++) {
> +		ret = request_irq(epf->db_msg[req].virq, epf_ntb_doorbell_handler,
>  				  0, "pci_epf_vntb_db", ntb);
>  
>  		if (ret) {
>  			dev_err(&epf->dev,
>  				"Failed to request doorbell IRQ: %d\n",
> -				epf->db_msg[i].virq);
> +				epf->db_msg[req].virq);
>  			goto err_free_irq;
>  		}
>  	}
> @@ -598,8 +599,8 @@ static int epf_ntb_db_bar_init_msi_doorbell(struct epf_ntb *ntb,
>  	return 0;
>  
>  err_free_irq:
> -	for (i--; i >= 0; i--)
> -		free_irq(epf->db_msg[i].virq, ntb);
> +	while (req)
> +		free_irq(epf->db_msg[--req].virq, ntb);

Please keep the for-loop.
Or if you want to change it, do so in a separate patch.


I understand that you need a separate variable for this,
since "i" is (re-)used in other places in the function,
but changing the for loop to a while is distracting from
the actual fix.


Kind regards,
Niklas