driver core: bus: bus_add/probe/remove_device() cleanups

Convert the bus_add_device(), bus_probe_device(), and
bus_remove_device() 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/20230208111330.439504-7-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 d30a07ff8ab2a02d07c8460b39cf16948898d30c..a32975028aee9bd1f465257a5f798cb614e5e351 100644 (file)
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -466,32 +466,46 @@ EXPORT_SYMBOL_GPL(bus_for_each_drv);
  */
 int bus_add_device(struct device *dev)
 {
-       struct bus_type *bus = bus_get(dev->bus);
-       int error = 0;
+       struct subsys_private *sp = bus_to_subsys(dev->bus);
+       int error;
 
-       if (bus) {
-               pr_debug("bus: '%s': add device %s\n", bus->name, dev_name(dev));
-               error = device_add_groups(dev, bus->dev_groups);
-               if (error)
-                       goto out_put;
-               error = sysfs_create_link(&bus->p->devices_kset->kobj,
-                                               &dev->kobj, dev_name(dev));
-               if (error)
-                       goto out_groups;
-               error = sysfs_create_link(&dev->kobj,
-                               &dev->bus->p->subsys.kobj, "subsystem");
-               if (error)
-                       goto out_subsys;
-               klist_add_tail(&dev->p->knode_bus, &bus->p->klist_devices);
+       if (!sp) {
+               /*
+                * This is a normal operation for many devices that do not
+                * have a bus assigned to them, just say that all went
+                * well.
+                */
+               return 0;
        }
+
+       /*
+        * Reference in sp is now incremented and will be dropped when
+        * the device is removed from the bus
+        */
+
+       pr_debug("bus: '%s': add device %s\n", sp->bus->name, dev_name(dev));
+
+       error = device_add_groups(dev, sp->bus->dev_groups);
+       if (error)
+               goto out_put;
+
+       error = sysfs_create_link(&sp->devices_kset->kobj, &dev->kobj, dev_name(dev));
+       if (error)
+               goto out_groups;
+
+       error = sysfs_create_link(&dev->kobj, &sp->subsys.kobj, "subsystem");
+       if (error)
+               goto out_subsys;
+
+       klist_add_tail(&dev->p->knode_bus, &sp->klist_devices);
        return 0;
 
 out_subsys:
-       sysfs_remove_link(&bus->p->devices_kset->kobj, dev_name(dev));
+       sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev));
 out_groups:
-       device_remove_groups(dev, bus->dev_groups);
+       device_remove_groups(dev, sp->bus->dev_groups);
 out_put:
-       bus_put(dev->bus);
+       subsys_put(sp);
        return error;
 }
 
@@ -503,20 +517,21 @@ out_put:
  */
 void bus_probe_device(struct device *dev)
 {
-       struct bus_type *bus = dev->bus;
+       struct subsys_private *sp = bus_to_subsys(dev->bus);
        struct subsys_interface *sif;
 
-       if (!bus)
+       if (!sp)
                return;
 
-       if (bus->p->drivers_autoprobe)
+       if (sp->drivers_autoprobe)
                device_initial_probe(dev);
 
-       mutex_lock(&bus->p->mutex);
-       list_for_each_entry(sif, &bus->p->interfaces, node)
+       mutex_lock(&sp->mutex);
+       list_for_each_entry(sif, &sp->interfaces, node)
                if (sif->add_dev)
                        sif->add_dev(dev, sif);
-       mutex_unlock(&bus->p->mutex);
+       mutex_unlock(&sp->mutex);
+       subsys_put(sp);
 }
 
 /**
@@ -531,21 +546,20 @@ void bus_probe_device(struct device *dev)
  */
 void bus_remove_device(struct device *dev)
 {
-       struct bus_type *bus = dev->bus;
+       struct subsys_private *sp = bus_to_subsys(dev->bus);
        struct subsys_interface *sif;
 
-       if (!bus)
+       if (!sp)
                return;
 
-       mutex_lock(&bus->p->mutex);
-       list_for_each_entry(sif, &bus->p->interfaces, node)
+       mutex_lock(&sp->mutex);
+       list_for_each_entry(sif, &sp->interfaces, node)
                if (sif->remove_dev)
                        sif->remove_dev(dev, sif);
-       mutex_unlock(&bus->p->mutex);
+       mutex_unlock(&sp->mutex);
 
        sysfs_remove_link(&dev->kobj, "subsystem");
-       sysfs_remove_link(&dev->bus->p->devices_kset->kobj,
-                         dev_name(dev));
+       sysfs_remove_link(&sp->devices_kset->kobj, dev_name(dev));
        device_remove_groups(dev, dev->bus->dev_groups);
        if (klist_node_attached(&dev->p->knode_bus))
                klist_del(&dev->p->knode_bus);
@@ -553,7 +567,14 @@ void bus_remove_device(struct device *dev)
        pr_debug("bus: '%s': remove device %s\n",
                 dev->bus->name, dev_name(dev));
        device_release_driver(dev);
-       bus_put(dev->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_device()
+        */
+       subsys_put(sp);
+       subsys_put(sp);
 }
 
 static int __must_check add_bind_files(struct device_driver *drv)