From adac0375380a7d3e50194cc5b03b676b0321bded Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Wed, 8 Feb 2023 12:13:17 +0100 Subject: [PATCH] driver core: bus: subsys_interface_register/unregister() cleanups 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" Link: https://lore.kernel.org/r/20230208111330.439504-9-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman --- 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 d515a83..b831173 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); -- 2.7.4