3 files changed, 48 insertions, 20 deletions

diff --git a/drivers/base/base.h b/drivers/base/base.h
index b6966511b0ca..b405436ee28e 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -65,6 +65,7 @@ struct driver_private {
  *	binding of drivers which were unable to get all the resources needed by
  *	the device; typically because it depends on another driver getting
  *	probed first.
+ * @async_driver - pointer to device driver awaiting probe via async_probe
  * @device - pointer back to the struct device that this structure is
  * associated with.
  * @dead - This device is currently either in the process of or has been
@@ -80,6 +81,7 @@ struct device_private {
 	struct klist_node knode_bus;
 	struct klist_node knode_class;
 	struct list_head deferred_probe;
+	struct device_driver *async_driver;
 	struct device *device;
 	u8 dead:1;
 };
diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index cfa5b63b5582..0a58e969f8b7 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -610,17 +610,6 @@ static ssize_t uevent_store(struct device_driver *drv, const char *buf,
 }
 static DRIVER_ATTR_WO(uevent);
 
-static void driver_attach_async(void *_drv, async_cookie_t cookie)
-{
-	struct device_driver *drv = _drv;
-	int ret;
-
-	ret = driver_attach(drv);
-
-	pr_debug("bus: '%s': driver %s async attach completed: %d\n",
-		 drv->bus->name, drv->name, ret);
-}
-
 /**
  * bus_add_driver - Add a driver to the bus.
  * @drv: driver.
@@ -653,15 +642,9 @@ int bus_add_driver(struct device_driver *drv)
 
 	klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
 	if (drv->bus->p->drivers_autoprobe) {
-		if (driver_allows_async_probing(drv)) {
-			pr_debug("bus: '%s': probing driver %s asynchronously\n",
-				drv->bus->name, drv->name);
-			async_schedule(driver_attach_async, drv);
-		} else {
-			error = driver_attach(drv);
-			if (error)
-				goto out_unregister;
-		}
+		error = driver_attach(drv);
+		if (error)
+			goto out_unregister;
 	}
 	module_add_driver(drv->owner, drv);
 
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 34556359c7da..627ad05064e0 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -925,6 +925,30 @@ int device_driver_attach(struct device_driver *drv, struct device *dev)
 	return ret;
 }
 
+static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
+{
+	struct device *dev = _dev;
+	struct device_driver *drv;
+	int ret = 0;
+
+	__device_driver_lock(dev, dev->parent);
+
+	drv = dev->p->async_driver;
+
+	/*
+	 * If device has been removed or someone has already successfully
+	 * bound a driver before us just skip the driver probe call.
+	 */
+	if (!dev->p->dead && !dev->driver)
+		ret = driver_probe_device(drv, dev);
+
+	__device_driver_unlock(dev, dev->parent);
+
+	dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
+
+	put_device(dev);
+}
+
 static int __driver_attach(struct device *dev, void *data)
 {
 	struct device_driver *drv = data;
@@ -952,6 +976,25 @@ static int __driver_attach(struct device *dev, void *data)
 		return ret;
 	} /* ret > 0 means positive match */
 
+	if (driver_allows_async_probing(drv)) {
+		/*
+		 * Instead of probing the device synchronously we will
+		 * probe it asynchronously to allow for more parallelism.
+		 *
+		 * We only take the device lock here in order to guarantee
+		 * that the dev->driver and async_driver fields are protected
+		 */
+		dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
+		device_lock(dev);
+		if (!dev->driver) {
+			get_device(dev);
+			dev->p->async_driver = drv;
+			async_schedule(__driver_attach_async_helper, dev);
+		}
+		device_unlock(dev);
+		return 0;
+	}
+
 	device_driver_attach(drv, dev);
 
 	return 0;