[PATCH] pci: fix no_pci_devices()

[Vegard Nossum]

In short, no_pci_devices() should not use bus_find_device() before
initcalls have run, because the pci bus structure has not been
initialized yet.

Reference: http://lkml.org/lkml/2008/12/20/21

Cc: Greg KH <gregkh@xxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxx>
---
 drivers/pci/pci-driver.c |   10 +++++++++-
 drivers/pci/probe.c      |    3 +++
 include/linux/pci.h      |    1 +
 3 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index b4cdd69..9e0215e 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -825,6 +825,8 @@ int pci_uevent(struct device *dev, struct kobj_uevent_env *env)
 }
 #endif
 
+int pci_is_initiated __read_mostly;
+
 struct bus_type pci_bus_type = {
 	.name		= "pci",
 	.match		= pci_bus_match,
@@ -838,7 +840,13 @@ struct bus_type pci_bus_type = {
 
 static int __init pci_driver_init(void)
 {
-	return bus_register(&pci_bus_type);
+	int ret;
+
+	ret = bus_register(&pci_bus_type);
+	if (ret == 0)
+		pci_is_initiated = 1;
+
+	return ret;
 }
 
 postcore_initcall(pci_driver_init);
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 003a9b3..1320a81 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -35,6 +35,9 @@ int no_pci_devices(void)
 	struct device *dev;
 	int no_devices;
 
+	if (!pci_is_initiated)
+		return 1;
+
 	dev = bus_find_device(&pci_bus_type, NULL, NULL, find_anything);
 	no_devices = (dev == NULL);
 	put_device(dev);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index feb4657..9e1b30f 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -484,6 +484,7 @@ extern struct bus_type pci_bus_type;
  * code, or pci core code. */
 extern struct list_head pci_root_buses;	/* list of all known PCI buses */
 /* Some device drivers need know if pci is initiated */
+extern int pci_is_initiated;
 extern int no_pci_devices(void);
 
 void pcibios_fixup_bus(struct pci_bus *);
-- 
1.5.6.5

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