PCI: Fix BUG on device attach failure

l1k · bjorn-helgaas · commit 1e398eae8407 · 2016-05-02T13:48:25.000-05:00
Previously when pci_bus_add_device() called device_attach() and it returned a negative value, we emitted a WARN but carried on. Commit ab1a187 ("PCI: Check device_attach() return value always"), introduced in Linux 4.6-rc1, changed this to unwind all steps preceding device_attach() and to not set dev->is_added = 1. The latter leads to a BUG if pci_bus_add_device() was called from pci_bus_add_devices(). Fix by not recursing to a child bus if device_attach() failed for the bridge leading to it. This can be triggered by plugging in a PCI device (e.g. Thunderbolt) while the system is asleep. The system locks up when woken because device_attach() returns -EPROBE_DEFER. Fixes: ab1a187 ("PCI: Check device_attach() return value always") Signed-off-by: Lukas Wunner <lukas@wunner.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
@@ -324,7 +324,9 @@ void pci_bus_add_devices(const struct pci_bus *bus)
 	}
 
 	list_for_each_entry(dev, &bus->devices, bus_list) {
-		BUG_ON(!dev->is_added);
+		/* Skip if device attach failed */
+		if (!dev->is_added)
+			continue;
 		child = dev->subordinate;
 		if (child)
 			pci_bus_add_devices(child);
