Re: [PATCH] PCI: endpoint: pci-epf-test: Roll back BAR mapping when subrange setup fails

[Niklas Cassel <cassel@kernel.org>]

On Mon, Mar 16, 2026 at 11:02:25PM +0900, Koichiro Den wrote:
> When the BAR subrange mapping test on DWC-based platforms fails due to
> insufficient free inbound iATU regions,
> pci_epf_test_bar_subrange_setup() returns an error (-ENOSPC) but does
> not restore the original BAR mapping. This causes subsequent test runs
> to become confusing, since the failure may leave room for the next
> subrange mapping test to pass.
> 
> Fix this by restoring the original BAR mapping when preparation of the
> subrange mapping fails, so that no side effect remains regardless of the
> test success or failure.
> 
> Fixes: 6c5e6101423b ("PCI: endpoint: pci-epf-test: Add BAR subrange mapping test support")
> Reported-by: Christian Bruel <christian.bruel@foss.st.com>
> Closes: https://lore.kernel.org/linux-pci/b2b03ebe-9482-4a13-b22f-7b44da096eed@foss.st.com/
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> ---
>  drivers/pci/endpoint/functions/pci-epf-test.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 14e61ebe1f11..f44c36f5cac5 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -898,16 +898,22 @@ static void pci_epf_test_bar_subrange_setup(struct pci_epf_test *epf_test,
>  	bar->submap = submap;
>  	bar->num_submap = nsub;
>  
>  	ret = pci_epc_set_bar(epc, epf->func_no, epf->vfunc_no, bar);
>  	if (ret) {
>  		dev_err(&epf->dev, "pci_epc_set_bar() failed: %d\n", ret);
>  		bar->submap = old_submap;
>  		bar->num_submap = old_nsub;
> +		ret = pci_epc_set_bar(epc, epf->func_no, epf->vfunc_no, bar);
> +		if (ret)
> +			dev_warn(&epf->dev,
> +				 "failed to restore the original BAR mapping: %d\n",

Nit:
I would use a capitalized F:
"Failed to restore ..."

in order to match most other prints in this file.

Reviewed-by: Niklas Cassel <cassel@kernel.org>