[PATCH] Add a klist to struct device_driver for the devices bound to it.

- Use it in driver_for_each_device() instead of the regular list_head and stop using
  the bus's rwsem for protection.
- Use driver_for_each_device() in driver_detach() so we don't deadlock on the
  bus's rwsem.
- Remove ->devices.
- Move klist access and sysfs link access out from under device's semaphore, since
  they're synchronized through other means.

Signed-off-by: Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 37 insertions, 29 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 93440824b800..bc5bec61a01a 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -209,8 +209,8 @@ void device_initialize(struct device *dev)
         kobject_init(&dev->kobj);
         INIT_LIST_HEAD(&dev->node);
         INIT_LIST_HEAD(&dev->children);
-        INIT_LIST_HEAD(&dev->driver_list);
         INIT_LIST_HEAD(&dev->bus_list);
+        INIT_LIST_HEAD(&dev->driver_list);
         INIT_LIST_HEAD(&dev->dma_pools);
         init_MUTEX(&dev->sem);
 }
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index b709b1e0cb2a..47cbb5641235 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -40,7 +40,7 @@ void device_bind_driver(struct device * dev)
 {
         pr_debug("bound device '%s' to driver '%s'\n",
                  dev->bus_id, dev->driver->name);
-        list_add_tail(&dev->driver_list, &dev->driver->devices);
+        klist_add_tail(&dev->driver->klist_devices, &dev->knode_driver);
         sysfs_create_link(&dev->driver->kobj, &dev->kobj,
                           kobject_name(&dev->kobj));
         sysfs_create_link(&dev->kobj, &dev->driver->kobj, "driver");
@@ -164,31 +164,35 @@ void driver_attach(struct device_driver * drv)
  */
 void device_release_driver(struct device * dev)
 {
-        struct device_driver * drv;
+        struct device_driver * drv = dev->driver;
+
+        if (!drv)
+                return;
+
+        sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
+        sysfs_remove_link(&dev->kobj, "driver");
+        klist_remove(&dev->knode_driver);
 
         down(&dev->sem);
-        drv = dev->driver;
-        if (drv) {
-                sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
-                sysfs_remove_link(&dev->kobj, "driver");
-                list_del_init(&dev->driver_list);
-                if (drv->remove)
-                        drv->remove(dev);
-                dev->driver = NULL;
-        }
+        if (drv->remove)
+                drv->remove(dev);
+        dev->driver = NULL;
         up(&dev->sem);
 }
 
+static int __remove_driver(struct device * dev, void * unused)
+{
+        device_release_driver(dev);
+        return 0;
+}
+
 /**
  * driver_detach - detach driver from all devices it controls.
  * @drv: driver.
  */
 void driver_detach(struct device_driver * drv)
 {
-        while (!list_empty(&drv->devices)) {
-                struct device * dev = container_of(drv->devices.next, struct device, driver_list);
-                device_release_driver(dev);
-        }
+        driver_for_each_device(drv, NULL, NULL, __remove_driver);
 }
 
 
diff --git a/drivers/base/driver.c b/drivers/base/driver.c
index 484fed1985aa..34bd38aa7eb8 100644
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -19,6 +19,12 @@
 #define to_drv(obj) container_of(obj, struct device_driver, kobj)
 
 
+static struct device * next_device(struct klist_iter * i)
+{
+        struct klist_node * n = klist_next(i);
+        return n ? container_of(n, struct device, knode_driver) : NULL;
+}
+
 /**
  *      driver_for_each_device - Iterator for devices bound to a driver.
  *      @drv:   Driver we're iterating.
@@ -32,21 +38,18 @@
 int driver_for_each_device(struct device_driver * drv, struct device * start, 
                            void * data, int (*fn)(struct device *, void *))
 {
-        struct list_head * head;
+        struct klist_iter i;
         struct device * dev;
         int error = 0;
 
-        down_read(&drv->bus->subsys.rwsem);
-        head = &drv->devices;
-        dev = list_prepare_entry(start, head, driver_list);
-        list_for_each_entry_continue(dev, head, driver_list) {
-                get_device(dev);
+        if (!drv)
+                return -EINVAL;
+
+        klist_iter_init_node(&drv->klist_devices, &i,
+                             start ? &start->knode_driver : NULL);
+        while ((dev = next_device(&i)) && !error)
                 error = fn(dev, data);
-                put_device(dev);
-                if (error)
-                        break;
-        }
-        up_read(&drv->bus->subsys.rwsem);
+        klist_iter_exit(&i);
         return error;
 }
 
@@ -120,7 +123,7 @@ void put_driver(struct device_driver * drv)
  */
 int driver_register(struct device_driver * drv)
 {
-        INIT_LIST_HEAD(&drv->devices);
+        klist_init(&drv->klist_devices);
         init_completion(&drv->unloaded);
         return bus_add_driver(drv);
 }
diff --git a/include/linux/device.h b/include/linux/device.h
index ea9ab33dfe71..96c71b59fdef 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -105,7 +105,7 @@ struct device_driver {
 
         struct completion       unloaded;
         struct kobject          kobj;
-        struct list_head        devices;
+        struct klist            klist_devices;
         struct klist_node       knode_bus;
 
         struct module           * owner;
@@ -266,6 +266,7 @@ struct device {
         struct list_head bus_list;      /* node in bus's list */
         struct list_head driver_list;
         struct list_head children;
+        struct klist_node       knode_driver;
         struct klist_node       knode_bus;
         struct device   * parent;