PCI: Limit visibility of match_driver flag to PCI core

Since commit 58d9a38 ("PCI: Skip attaching driver in device_add()"),
PCI enumeration is split into two steps:  In the first step, all devices
are published in sysfs with device_add().  In the second step, drivers are
bound to the devices with device_attach().  To delay driver binding until
the second step, a "bool match_driver" in struct pci_dev is used.

Instead of a bool, use a bit in the "unsigned long priv_flags" to shrink
struct pci_dev a little and prevent use of the bool outside the PCI core
(as has happened with commit cbbc00b ("iommu/amd: Prevent binding
other PCI drivers to IOMMU PCI devices")).

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Link: https://patch.msgid.link/d22a9e5b81d6bd8dd1837607d6156679b3b1199c.1745572340.git.lukas@wunner.de

Author: l1k

drivers/pci/bus.c

@@ -369,7 +369,9 @@ void pci_bus_add_device(struct pci_dev *dev)
 				pdev->name);
 	}
 
-	dev->match_driver = !dn || of_device_is_available(dn);
+	if (!dn || of_device_is_available(dn))
+		pci_dev_allow_binding(dev);
+
 	retval = device_attach(&dev->dev);
 	if (retval < 0 && retval != -EPROBE_DEFER)
 		pci_warn(dev, "device attach failed (%d)\n", retval);

drivers/pci/pci-driver.c

@@ -1507,7 +1507,7 @@ static int pci_bus_match(struct device *dev, const struct device_driver *drv)
 	struct pci_driver *pci_drv;
 	const struct pci_device_id *found_id;
 
-	if (!pci_dev->match_driver)
+	if (pci_dev_binding_disallowed(pci_dev))
 		return 0;
 
 	pci_drv = (struct pci_driver *)to_pci_driver(drv);

drivers/pci/pci.h

@@ -557,6 +557,7 @@ static inline int pci_dev_set_disconnected(struct pci_dev *dev, void *unused)
 #define PCI_DPC_RECOVERED 1
 #define PCI_DPC_RECOVERING 2
 #define PCI_DEV_REMOVED 3
+#define PCI_DEV_ALLOW_BINDING 7
 
 static inline void pci_dev_assign_added(struct pci_dev *dev)
 {
@@ -580,6 +581,16 @@ static inline bool pci_dev_test_and_set_removed(struct pci_dev *dev)
 	return test_and_set_bit(PCI_DEV_REMOVED, &dev->priv_flags);
 }
 
+static inline void pci_dev_allow_binding(struct pci_dev *dev)
+{
+	set_bit(PCI_DEV_ALLOW_BINDING, &dev->priv_flags);
+}
+
+static inline bool pci_dev_binding_disallowed(struct pci_dev *dev)
+{
+	return !test_bit(PCI_DEV_ALLOW_BINDING, &dev->priv_flags);
+}
+
 #ifdef CONFIG_PCIEAER
 #include <linux/aer.h>
 

drivers/pci/probe.c

@@ -2711,7 +2711,6 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
 	pci_set_msi_domain(dev);
 
 	/* Notifier could use PCI capabilities */
-	dev->match_driver = false;
 	ret = device_add(&dev->dev);
 	WARN_ON(ret < 0);
 

include/linux/pci.h

@@ -423,8 +423,6 @@ struct pci_dev {
 	struct resource resource[DEVICE_COUNT_RESOURCE]; /* I/O and memory regions + expansion ROMs */
 	struct resource driver_exclusive_resource;	 /* driver exclusive resource ranges */
 
-	bool		match_driver;		/* Skip attaching driver */
-
 	unsigned int	transparent:1;		/* Subtractive decode bridge */
 	unsigned int	io_window:1;		/* Bridge has I/O window */
 	unsigned int	pref_window:1;		/* Bridge has pref mem window */