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-rw-r--r--drivers/pci/search.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index 45f2b20ef513..fab381ed853c 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;