driver-core: fix race between device_register and driver_register

When a device is registered to a bus it will be a) added to the list
of devices of the bus and b) bind to a driver (if one matches). As a
result of a driver being registered at this bus between a) and b) this
device could already be bound to a driver. This leads to a warning
and incorrect refcounting.
To fix this add a check to device_attach to identify an already bound
device.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index da57ee9d63fe..7e9219b02796 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -245,6 +245,10 @@ int device_attach(struct device *dev)
 
         device_lock(dev);
         if (dev->driver) {
+                if (klist_node_attached(&dev->p->knode_driver)) {
+                        ret = 1;
+                        goto out_unlock;
+                }
                 ret = device_bind_driver(dev);
                 if (ret == 0)
                         ret = 1;
@@ -257,6 +261,7 @@ int device_attach(struct device *dev)
                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
                 pm_runtime_put_sync(dev);
         }
+out_unlock:
         device_unlock(dev);
         return ret;
 }