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

[Koichiro Den]

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@xxxxxxxxxxx>
Closes: https://lore.kernel.org/linux-pci/b2b03ebe-9482-4a13-b22f-7b44da096eed@xxxxxxxxxxx/
Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>
---
 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",
+				 ret);
+
 		kfree(submap);
 		goto err;
 	}
 	kfree(old_submap);
 
 	/*
 	 * Fill deterministic signatures into the physical regions that
 	 * each BAR subrange maps to. RC verifies these to ensure the
-- 
2.51.0