linux-kernel - [PATCH 15/24] PCI: Use pbus_select

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Message-Id: <20250822145605.18172-16-ilpo.jarvinen@linux.intel.com>
Date: Fri, 22 Aug 2025 17:55:56 +0300
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Andreas Larsson <andreas@...sler.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"David S. Miller" <davem@...emloft.net>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	linux-m68k@...ts.linux-m68k.org,
	linux-mips@...r.kernel.org,
	linux-pci@...r.kernel.org,
	sparclinux@...r.kernel.org,
	Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
	Christian König <christian.koenig@....com>,
	Yinghai Lu <yinghai@...nel.org>,
	Igor Mammedov <imammedo@...hat.com>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Krzysztof Wilczyński <kw@...ux.com>,
	linux-kernel@...r.kernel.org
Cc: Michał Winiarski <michal.winiarski@...el.com>,
	linuxppc-dev@...ts.ozlabs.org,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH 15/24] PCI: Use pbus_select_window() during BAR resize

Prior to a BAR resize, __resource_resize_store() loops through the
normal resources of the PCI device and releases those that match to the
flags of the BAR to be resized. This is necessary to allow resizing
also the upstream bridge window as only childless bridge windows can be
resized.

While the flags check (mostly) works (if corner cases are ignored), the
more straightforward way is to check if the resources share the bridge
window. Change __resource_resize_store() to do the check using
pbus_select_window().

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---
 drivers/pci/pci-sysfs.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 162a5241c7f7..ce3923c4aa80 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1562,13 +1562,19 @@ static ssize_t __resource_resize_store(struct device *dev, int n,
 				       const char *buf, size_t count)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
-	unsigned long size, flags;
+	struct pci_bus *bus = pdev->bus;
+	struct resource *b_win, *res;
+	unsigned long size;
 	int ret, i;
 	u16 cmd;
 
 	if (kstrtoul(buf, 0, &size) < 0)
 		return -EINVAL;
 
+	b_win = pbus_select_window(bus, pci_resource_n(pdev, n));
+	if (!b_win)
+		return -EINVAL;
+
 	device_lock(dev);
 	if (dev->driver || pci_num_vf(pdev)) {
 		ret = -EBUSY;
@@ -1588,19 +1594,19 @@ static ssize_t __resource_resize_store(struct device *dev, int n,
 	pci_write_config_word(pdev, PCI_COMMAND,
 			      cmd & ~PCI_COMMAND_MEMORY);
 
-	flags = pci_resource_flags(pdev, n);
-
 	pci_remove_resource_files(pdev);
 
-	for (i = 0; i < PCI_BRIDGE_RESOURCES; i++) {
-		if (pci_resource_len(pdev, i) &&
-		    pci_resource_flags(pdev, i) == flags)
+	pci_dev_for_each_resource(pdev, res, i) {
+		if (i >= PCI_BRIDGE_RESOURCES)
+			break;
+
+		if (b_win == pbus_select_window(bus, res))
 			pci_release_resource(pdev, i);
 	}
 
 	ret = pci_resize_resource(pdev, n, size);
 
-	pci_assign_unassigned_bus_resources(pdev->bus);
+	pci_assign_unassigned_bus_resources(bus);
 
 	if (pci_create_resource_files(pdev))
 		pci_warn(pdev, "Failed to recreate resource files after BAR resizing\n");
-- 
2.39.5