[PATCH 11/21] driver core: bus: bus_add/remove_driver() cleanups

Greg Kroah-Hartman
2023-02-08T11:14:36Z

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/base/bus.c | 39 ++++++++++++++++++++++++++-------------
1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index f23c6f6306e2..b594804c716d 100644
--- 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 @@ int bus_add_driver(struct device_driver *drv)
/* 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 @@ int bus_add_driver(struct device_driver *drv)
*/
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 */
--
2.39.1