1 files changed, 45 insertions, 17 deletions

diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index 2f13eba5d5a..fab381ed853 100644
--- 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;
 
@@ -413,6 +437,24 @@ exit:
 	return dev;
 }
 
+const struct pci_device_id *pci_find_present(const struct pci_device_id *ids)
+{
+	struct pci_dev *dev;
+	const struct pci_device_id *found = NULL;
+
+	WARN_ON(in_interrupt());
+	down_read(&pci_bus_sem);
+	while (ids->vendor || ids->subvendor || ids->class_mask) {
+		list_for_each_entry(dev, &pci_devices, global_list) {
+			if ((found = pci_match_one_device(ids, dev)) != NULL)
+				break;
+		}
+		ids++;
+	}
+	up_read(&pci_bus_sem);
+	return found;
+}
+
 /**
  * pci_dev_present - Returns 1 if device matching the device list is present, 0 if not.
  * @ids: A pointer to a null terminated list of struct pci_device_id structures
@@ -426,25 +468,11 @@ exit:
  */
 int pci_dev_present(const struct pci_device_id *ids)
 {
-	struct pci_dev *dev;
-	int found = 0;
-
-	WARN_ON(in_interrupt());
-	down_read(&pci_bus_sem);
-	while (ids->vendor || ids->subvendor || ids->class_mask) {
-		list_for_each_entry(dev, &pci_devices, global_list) {
-			if (pci_match_one_device(ids, dev)) {
-				found = 1;
-				goto exit;
-			}
-		}
-		ids++;
-	}
-exit:
-	up_read(&pci_bus_sem);
-	return found;
+	return pci_find_present(ids) == NULL ? 0 : 1;
 }
+
 EXPORT_SYMBOL(pci_dev_present);
+EXPORT_SYMBOL(pci_find_present);
 
 EXPORT_SYMBOL(pci_find_device);
 EXPORT_SYMBOL(pci_find_device_reverse);