Merge branch 'ftape' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik/misc-2.6

[powerpc.git] / drivers / pci / search.c

diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index 45f2b20..fab381e 100644 (file)
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -193,6 +193,18 @@ static struct pci_dev * pci_find_subsys(unsigned int vendor,
        struct pci_dev *dev;
 
        WARN_ON(in_interrupt());
+
+       /*
+        * pci_find_subsys() can be called on the ide_setup() path, super-early
+        * in boot.  But the down_read() will enable local interrupts, which
+        * can cause some machines to crash.  So here we detect and flag that
+        * situation and bail out early.
+        */
+       if (unlikely(list_empty(&pci_devices))) {
+               printk(KERN_INFO "pci_find_subsys() called while pci_devices "
+                               "is still empty\n");
+               return NULL;
+       }
        down_read(&pci_bus_sem);
        n = from ? from->global_list.next : pci_devices.next;
 
@@ -259,6 +271,18 @@ pci_get_subsys(unsigned int vendor, unsigned int device,
        struct pci_dev *dev;
 
        WARN_ON(in_interrupt());
+
+       /*
+        * pci_get_subsys() can potentially be called by drivers super-early
+        * in boot.  But the down_read() will enable local interrupts, which
+        * can cause some machines to crash.  So here we detect and flag that
+        * situation and bail out early.
+        */
+       if (unlikely(list_empty(&pci_devices))) {
+               printk(KERN_NOTICE "pci_get_subsys() called while pci_devices "
+                               "is still empty\n");
+               return NULL;
+       }
        down_read(&pci_bus_sem);
        n = from ? from->global_list.next : pci_devices.next;