linux-kernel - [PATCH v2 14/24] PCI: Warn if bridge window cannot be released when resizing BAR

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Message-Id: <20250829131113.36754-15-ilpo.jarvinen@linux.intel.com>
Date: Fri, 29 Aug 2025 16:11:03 +0300
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-pci@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH v2 14/24] 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@...ux.intel.com>
---
 drivers/pci/setup-bus.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 4b08b9cecab3..47f1a4747607 100644
--- 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;
-- 
2.39.5