[PATCH 3/5 v2] PCI: Add locking to pci_find_upstream_pcie_bridge()

[Stefan Assmann <sassmann@redhat.com>]

From: Stefan Assmann <sassmann@redhat.com>

pci_find_upstream_pcie_bridge() should take the pci_bus_sem semaphore while
reading global PCI structures.

Signed-off-by: Stefan Assmann <sassmann@redhat.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/pci/search.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index 9d75dc8..c8159b0 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -29,6 +29,8 @@ pci_find_upstream_pcie_bridge(struct pci_dev *pdev)
 
 	if (pci_is_pcie(pdev))
 		return NULL;
+
+	down_read(&pci_bus_sem);
 	while (1) {
 		if (pci_is_root_bus(pdev->bus))
 			break;
@@ -38,6 +40,7 @@ pci_find_upstream_pcie_bridge(struct pci_dev *pdev)
 			tmp = pdev;
 			continue;
 		}
+		up_read(&pci_bus_sem);
 		/* PCI device should connect to a PCIe bridge */
 		if (pdev->pcie_type != PCI_EXP_TYPE_PCI_BRIDGE) {
 			/* Busted hardware? */
@@ -46,6 +49,7 @@ pci_find_upstream_pcie_bridge(struct pci_dev *pdev)
 		}
 		return pdev;
 	}
+	up_read(&pci_bus_sem);
 
 	return tmp;
 }
-- 
1.7.3.2