[PATCH 06/21] driver core: bus: bus_add/probe/remove_device() cleanups

Greg Kroah-Hartman
2023-02-08T11:15:38Z

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/base/bus.c | 87 ++++++++++++++++++++++++++++------------------
1 file changed, 54 insertions(+), 33 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index f0d3ad41fd5e..f4e4efd81b29 100644
--- 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 @@ int bus_add_device(struct device *dev)
*/
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)
--
2.39.1