PCI: Warn if bridge window cannot be released when resizing BAR

BAR resizing calls to pci_reassign_bridge_resources(), which attempts to
release any upstream bridge window to allow them to accommodate the new BAR
size. The release can only be performed if there are no other child
resources for the bridge window. Previously the code continued silently
when other child resources were detected.

Add pci_warn() to inform user that a bridge window could not be released
because of child resources. As a small bridge window is often the reason
why BAR resize fails, this warning will help to pinpoint to the cause.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20250829131113.36754-15-ilpo.jarvinen@linux.intel.com

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 4b08b9cecab3f3858672d854284b31427b006383..47f1a4747607ec3af9a461974f37637718b1e267 100644 (file)
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -2555,6 +2555,12 @@ int pbus_reassign_bridge_resources(struct pci_bus *bus, struct resource *res)
                                goto cleanup;
 
                        pci_release_resource(bridge, i);
+               } else {
+                       const char *res_name = pci_resource_name(bridge, i);
+
+                       pci_warn(bridge,
+                                "%s %pR: was not released (still contains assigned resources)\n",
+                                res_name, res);
                }
 
                bus = bus->parent;