driver core: bus: bus_add/remove_driver() cleanups

Convert the bus_add_driver() and bus_remove_driver() functions to use
bus_to_subsys() and not use the back-pointer to the private structure.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230208111330.439504-12-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 81c0f7f..eb8fb42 100644 (file)
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -636,15 +636,18 @@ static DRIVER_ATTR_WO(uevent);
  */
 int bus_add_driver(struct device_driver *drv)
 {
-       struct bus_type *bus;
+       struct subsys_private *sp = bus_to_subsys(drv->bus);
        struct driver_private *priv;
        int error = 0;
 
-       bus = bus_get(drv->bus);
-       if (!bus)
+       if (!sp)
                return -EINVAL;
 
-       pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name);
+       /*
+        * Reference in sp is now incremented and will be dropped when
+        * the driver is removed from the bus
+        */
+       pr_debug("bus: '%s': add driver %s\n", sp->bus->name, drv->name);
 
        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        if (!priv) {
@@ -654,14 +657,14 @@ int bus_add_driver(struct device_driver *drv)
        klist_init(&priv->klist_devices, NULL, NULL);
        priv->driver = drv;
        drv->p = priv;
-       priv->kobj.kset = bus->p->drivers_kset;
+       priv->kobj.kset = sp->drivers_kset;
        error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
                                     "%s", drv->name);
        if (error)
                goto out_unregister;
 
-       klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
-       if (drv->bus->p->drivers_autoprobe) {
+       klist_add_tail(&priv->knode_bus, &sp->klist_drivers);
+       if (sp->drivers_autoprobe) {
                error = driver_attach(drv);
                if (error)
                        goto out_del_list;
@@ -673,7 +676,7 @@ int bus_add_driver(struct device_driver *drv)
                printk(KERN_ERR "%s: uevent attr (%s) failed\n",
                        __func__, drv->name);
        }
-       error = driver_add_groups(drv, bus->drv_groups);
+       error = driver_add_groups(drv, sp->bus->drv_groups);
        if (error) {
                /* How the hell do we get out of this pickle? Give up */
                printk(KERN_ERR "%s: driver_add_groups(%s) failed\n",
@@ -698,7 +701,7 @@ out_unregister:
        /* drv->p is freed in driver_release()  */
        drv->p = NULL;
 out_put_bus:
-       bus_put(bus);
+       subsys_put(sp);
        return error;
 }
 
@@ -712,19 +715,29 @@ out_put_bus:
  */
 void bus_remove_driver(struct device_driver *drv)
 {
-       if (!drv->bus)
+       struct subsys_private *sp = bus_to_subsys(drv->bus);
+
+       if (!sp)
                return;
 
+       pr_debug("bus: '%s': remove driver %s\n", sp->bus->name, drv->name);
+
        if (!drv->suppress_bind_attrs)
                remove_bind_files(drv);
-       driver_remove_groups(drv, drv->bus->drv_groups);
+       driver_remove_groups(drv, sp->bus->drv_groups);
        driver_remove_file(drv, &driver_attr_uevent);
        klist_remove(&drv->p->knode_bus);
-       pr_debug("bus: '%s': remove driver %s\n", drv->bus->name, drv->name);
        driver_detach(drv);
        module_remove_driver(drv);
        kobject_put(&drv->p->kobj);
-       bus_put(drv->bus);
+
+       /*
+        * Decrement the reference count twice, once for the bus_to_subsys()
+        * call in the start of this function, and the second one from the
+        * reference increment in bus_add_driver()
+        */
+       subsys_put(sp);
+       subsys_put(sp);
 }
 
 /* Helper for bus_rescan_devices's iter */