[PATCH 08/21] driver core: bus: subsys_interface_register/unregister() cleanups

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

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

This also requires changing the parameters on subsys_dev_iter_init() to
iterate over the list properly.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/base/bus.c | 45 +++++++++++++++++++++++++++++----------------
1 file changed, 29 insertions(+), 16 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 549e55dfbfda..deed62509a62 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -1023,7 +1023,7 @@ struct subsys_dev_iter {
/**
* subsys_dev_iter_init - initialize subsys device iterator
* @iter: subsys iterator to initialize
- * @subsys: the subsys we wanna iterate over
+ * @sp: the subsys private (i.e. bus) we wanna iterate over
* @start: the device to start iterating from, if any
* @type: device_type of the devices to iterate over, NULL for all
*
@@ -1032,14 +1032,14 @@ struct subsys_dev_iter {
* otherwise if it is NULL, the iteration starts at the beginning of
* the list.
*/
-static void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
+static void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct subsys_private *sp,
struct device *start, const struct device_type *type)
{
struct klist_node *start_knode = NULL;

if (start)
start_knode = &start->p->knode_bus;
- klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
+ klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
iter->type = type;
}

@@ -1084,26 +1084,31 @@ static void subsys_dev_iter_exit(struct subsys_dev_iter *iter)

int subsys_interface_register(struct subsys_interface *sif)
{
- struct bus_type *subsys;
+ struct subsys_private *sp;
struct subsys_dev_iter iter;
struct device *dev;

if (!sif || !sif->subsys)
return -ENODEV;

- subsys = bus_get(sif->subsys);
- if (!subsys)
+ sp = bus_to_subsys(sif->subsys);
+ if (!sp)
return -EINVAL;

- mutex_lock(&subsys->p->mutex);
- list_add_tail(&sif->node, &subsys->p->interfaces);
+ /*
+ * Reference in sp is now incremented and will be dropped when
+ * the interface is removed from the bus
+ */
+
+ mutex_lock(&sp->mutex);
+ list_add_tail(&sif->node, &sp->interfaces);
if (sif->add_dev) {
- subsys_dev_iter_init(&iter, subsys, NULL, NULL);
+ subsys_dev_iter_init(&iter, sp, NULL, NULL);
while ((dev = subsys_dev_iter_next(&iter)))
sif->add_dev(dev, sif);
subsys_dev_iter_exit(&iter);
}
- mutex_unlock(&subsys->p->mutex);
+ mutex_unlock(&sp->mutex);

return 0;
}
@@ -1111,26 +1116,34 @@ EXPORT_SYMBOL_GPL(subsys_interface_register);

void subsys_interface_unregister(struct subsys_interface *sif)
{
- struct bus_type *subsys;
+ struct subsys_private *sp;
struct subsys_dev_iter iter;
struct device *dev;

if (!sif || !sif->subsys)
return;

- subsys = sif->subsys;
+ sp = bus_to_subsys(sif->subsys);
+ if (!sp)
+ return;

- mutex_lock(&subsys->p->mutex);
+ mutex_lock(&sp->mutex);
list_del_init(&sif->node);
if (sif->remove_dev) {
- subsys_dev_iter_init(&iter, subsys, NULL, NULL);
+ subsys_dev_iter_init(&iter, sp, NULL, NULL);
while ((dev = subsys_dev_iter_next(&iter)))
sif->remove_dev(dev, sif);
subsys_dev_iter_exit(&iter);
}
- mutex_unlock(&subsys->p->mutex);
+ mutex_unlock(&sp->mutex);

- bus_put(subsys);
+ /*
+ * 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 subsys_interface_register()
+ */
+ subsys_put(sp);
+ subsys_put(sp);
}
EXPORT_SYMBOL_GPL(subsys_interface_unregister);

--
2.39.1