[PATCH 1/2] misc: pci_endpoint_test: Give disabled BARs a distinct error code

[Niklas Cassel <cassel@kernel.org>]

The current code returns -ENOMEM if test->bar[barno] is NULL.

There can be two reasons why test->bar[barno] is NULL:
1) The pci_ioremap_bar() call in pci_endpoint_test_probe() failed.
2) The BAR was skipped, because it is disabled by the endpoint.

Many PCI endpoint controller drivers will disable all BARs in their
init function. A disabled BAR will have a size of 0.

A PCI endpoint function driver will be able to enable any BAR that
is not marked as BAR_RESERVED (which means that the BAR should not
be touched by the EPF driver).

Thus, perform check if the size is 0, before checking if
test->bar[barno] is NULL, such that we can return different errors.

This will allow the selftests to return SKIP instead of FAIL for
disabled BARs.

Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
Hello PCI maintainers.
This patch might give a trivial conflict with:
https://lore.kernel.org/linux-pci/20250123095906.3578241-2-cassel@kernel.org/T/#u
because the context lines (lines that haven't been changed)
might be different. If there is a conflict, simply look at
this patch by itself, and resolution should be trivial.

 drivers/misc/pci_endpoint_test.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
index d5ac71a49386..b95980b29eb9 100644
--- a/drivers/misc/pci_endpoint_test.c
+++ b/drivers/misc/pci_endpoint_test.c
@@ -292,11 +292,13 @@ static int pci_endpoint_test_bar(struct pci_endpoint_test *test,
 	void *read_buf __free(kfree) = NULL;
 	struct pci_dev *pdev = test->pdev;
 
+	bar_size = pci_resource_len(pdev, barno);
+	if (!bar_size)
+		return -ENODATA;
+
 	if (!test->bar[barno])
 		return -ENOMEM;
 
-	bar_size = pci_resource_len(pdev, barno);
-
 	if (barno == test->test_reg_bar)
 		bar_size = 0x4;
 
-- 
2.48.1