PCI: Skip attaching driver in device_add()

We want to add PCI devices to the device tree as early as possible but
delay attaching drivers.

device_add() adds a device to the device hierarchy and (via
device_attach()) attaches a matching driver and calls its .probe() method.
We want to separate adding the device to the hierarchy from attaching the
driver.

This patch does that by adding "match_driver" in struct pci_dev.  When
false, we return failure from pci_bus_match(), which makes device_attach()
believe there's no matching driver.

Later, we set "match_driver = true" and call device_attach() again, which
now attaches the driver and calls its .probe() method.

[bhelgaas: changelog, explicitly init dev->match_driver,
fold device_attach() call into pci_bus_add_device()]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 847f3ca47bb8..c8709c6fdb7c 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -177,10 +177,15 @@ int pci_bus_add_device(struct pci_dev *dev)
         if (retval)
                 return retval;
 
+        dev->match_driver = false;
         retval = device_add(&dev->dev);
         if (retval)
                 return retval;
 
+        dev->match_driver = true;
+        retval = device_attach(&dev->dev);
+        WARN_ON(retval < 0);
+
         dev->is_added = 1;
         pci_proc_attach_device(dev);
         pci_create_sysfs_dev_files(dev);