PCI/sysfs: Limit BAR resize attribute scope to platforms with PCI mmap

Currently, __resource_resize_store() uses sysfs_remove_groups() and
sysfs_create_groups() on pci_dev_resource_attr_groups to tear down and
recreate the resourceN files after a BAR resize, so the updated BAR sizes
are visible in sysfs.

The resourceN files only exist on platforms that define HAVE_PCI_MMAP or
ARCH_GENERIC_PCI_MMAP_RESOURCE.  On platforms that define neither,
pci_dev_resource_attr_groups is NULL and the sysfs_remove_groups() and
sysfs_create_groups() calls in __resource_resize_store() become no-ops.

Resizable BAR (ReBAR) is a PCI Express Extended Capability
(PCI_EXT_CAP_ID_REBAR) that requires PCIe extended config space.  Every
PCIe-capable architecture defines HAVE_PCI_MMAP or
ARCH_GENERIC_PCI_MMAP_RESOURCE (via arch headers or the asm-generic/pci.h
fallback).  Architectures without either only support conventional PCI and
cannot have any ReBAR-capable devices.

Move the resize show and store helpers, the per-BAR attribute definitions,
and the attribute group behind the existing #ifdef HAVE_PCI_MMAP ||
ARCH_GENERIC_PCI_MMAP_RESOURCE guard, and fold the group reference in
pci_dev_groups[] into the existing #if block.

Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Link: https://patch.msgid.link/20260508043543.217179-25-kwilczynski@kernel.org

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 15969930b4d184300d3934214213b521d8bbc9f7..d4b5f385a6cd880edc9a88b930e82afb91954854 100644 (file)
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1661,6 +1661,7 @@ static const struct attribute_group pci_dev_reset_method_attr_group = {
        .is_visible = pci_dev_reset_attr_is_visible,
 };
 
+#if defined(HAVE_PCI_MMAP) || defined(ARCH_GENERIC_PCI_MMAP_RESOURCE)
 static ssize_t __resource_resize_show(struct device *dev, int n, char *buf)
 {
        struct pci_dev *pdev = to_pci_dev(dev);
@@ -1775,6 +1776,7 @@ static const struct attribute_group pci_dev_resource_resize_attr_group = {
        .attrs = resource_resize_attrs,
        .is_visible = resource_resize_attr_is_visible,
 };
+#endif
 
 static struct attribute *pci_dev_dev_attrs[] = {
        &dev_attr_boot_vga.attr,
@@ -1849,8 +1851,8 @@ const struct attribute_group *pci_dev_groups[] = {
        &pci_dev_resource_io_attr_group,
        &pci_dev_resource_uc_attr_group,
        &pci_dev_resource_wc_attr_group,
-#endif
        &pci_dev_resource_resize_attr_group,
+#endif
        &pci_dev_config_attr_group,
        &pci_dev_rom_attr_group,
        &pci_dev_reset_attr_group,