[PATCH 27/62] pci: Fix locking in pci_do_resource_release_and_resize() error paths

[Bart Van Assche]

From: Bart Van Assche <bvanassche@xxxxxxx>

Make sure that down(&pci_bus_sem) has been called before
up(&pci_bus_sem) is called. This has been detected by the Clang
thread-safety analyzer. Compile-tested only.

Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Cc: linux-pci@xxxxxxxxxxxxxxx
Fixes: 337b1b566db0 ("PCI: Fix restoring BARs on BAR resize rollback path")
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
 drivers/pci/setup-bus.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 61f769aaa2f6..3bb8cd9a581e 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -2346,6 +2346,7 @@ int pci_do_resource_release_and_resize(struct pci_dev *pdev, int resno, int size
 	if (ret)
 		return ret;
 
+	down_read(&pci_bus_sem);
 	pci_dev_for_each_resource(pdev, r, i) {
 		if (i >= PCI_BRIDGE_RESOURCES)
 			break;
@@ -2367,7 +2368,6 @@ int pci_do_resource_release_and_resize(struct pci_dev *pdev, int resno, int size
 	if (!bus->self)
 		goto out;
 
-	down_read(&pci_bus_sem);
 	ret = pbus_reassign_bridge_resources(bus, res, &saved);
 	if (ret)
 		goto restore;