From d73ce004225a7b2ed75f4340bb63721d55552265 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 12 Mar 2013 11:30:05 -0700 Subject: [PATCH] driver/base: implement subsys_virtual_register() Kay tells me the most appropriate place to expose workqueues to userland would be /sys/devices/virtual/workqueues/WQ_NAME which is symlinked to /sys/bus/workqueue/devices/WQ_NAME and that we're lacking a way to do that outside of driver core as virtual_device_parent() isn't exported and there's no inteface to conveniently create a virtual subsystem. This patch implements subsys_virtual_register() by factoring out subsys_register() from subsys_system_register() and using it with virtual_device_parent() as the origin directory. It's identical to subsys_system_register() other than the origin directory but we aren't gonna restrict the device names which should be used under it. This will be used to expose workqueue attributes to userland. Signed-off-by: Tejun Heo Acked-by: Greg Kroah-Hartman Cc: Kay Sievers --- drivers/base/base.h | 2 + drivers/base/bus.c | 103 +++++++++++++++++++++++++++-------------- drivers/base/core.c | 2 +- include/linux/device.h | 2 + 4 files changed, 72 insertions(+), 37 deletions(-) diff --git a/drivers/base/base.h b/drivers/base/base.h index 6ee17bb391a9..b8bdfe61daa6 100644 --- a/drivers/base/base.h +++ b/drivers/base/base.h @@ -101,6 +101,8 @@ static inline int hypervisor_init(void) { return 0; } extern int platform_bus_init(void); extern void cpu_dev_init(void); +struct kobject *virtual_device_parent(struct device *dev); + extern int bus_add_device(struct device *dev); extern void bus_probe_device(struct device *dev); extern void bus_remove_device(struct device *dev); diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 519865b53f76..2ae2d2f92b6b 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -1205,6 +1205,49 @@ static void system_root_device_release(struct device *dev) { kfree(dev); } + +static int subsys_register(struct bus_type *subsys, + const struct attribute_group **groups, + struct kobject *parent_of_root) +{ + struct device *dev; + int err; + + err = bus_register(subsys); + if (err < 0) + return err; + + dev = kzalloc(sizeof(struct device), GFP_KERNEL); + if (!dev) { + err = -ENOMEM; + goto err_dev; + } + + err = dev_set_name(dev, "%s", subsys->name); + if (err < 0) + goto err_name; + + dev->kobj.parent = parent_of_root; + dev->groups = groups; + dev->release = system_root_device_release; + + err = device_register(dev); + if (err < 0) + goto err_dev_reg; + + subsys->dev_root = dev; + return 0; + +err_dev_reg: + put_device(dev); + dev = NULL; +err_name: + kfree(dev); +err_dev: + bus_unregister(subsys); + return err; +} + /** * subsys_system_register - register a subsystem at /sys/devices/system/ * @subsys: system subsystem @@ -1226,45 +1269,33 @@ static void system_root_device_release(struct device *dev) int subsys_system_register(struct bus_type *subsys, const struct attribute_group **groups) { - struct device *dev; - int err; - - err = bus_register(subsys); - if (err < 0) - return err; - - dev = kzalloc(sizeof(struct device), GFP_KERNEL); - if (!dev) { - err = -ENOMEM; - goto err_dev; - } - - err = dev_set_name(dev, "%s", subsys->name); - if (err < 0) - goto err_name; - - dev->kobj.parent = &system_kset->kobj; - dev->groups = groups; - dev->release = system_root_device_release; - - err = device_register(dev); - if (err < 0) - goto err_dev_reg; - - subsys->dev_root = dev; - return 0; - -err_dev_reg: - put_device(dev); - dev = NULL; -err_name: - kfree(dev); -err_dev: - bus_unregister(subsys); - return err; + return subsys_register(subsys, groups, &system_kset->kobj); } EXPORT_SYMBOL_GPL(subsys_system_register); +/** + * subsys_virtual_register - register a subsystem at /sys/devices/virtual/ + * @subsys: virtual subsystem + * @groups: default attributes for the root device + * + * All 'virtual' subsystems have a /sys/devices/system/ root device + * with the name of the subystem. The root device can carry subsystem-wide + * attributes. All registered devices are below this single root device. + * There's no restriction on device naming. This is for kernel software + * constructs which need sysfs interface. + */ +int subsys_virtual_register(struct bus_type *subsys, + const struct attribute_group **groups) +{ + struct kobject *virtual_dir; + + virtual_dir = virtual_device_parent(NULL); + if (!virtual_dir) + return -ENOMEM; + + return subsys_register(subsys, groups, virtual_dir); +} + int __init buses_init(void) { bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL); diff --git a/drivers/base/core.c b/drivers/base/core.c index 56536f4b0f6b..f58084a86e8c 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -690,7 +690,7 @@ void device_initialize(struct device *dev) set_dev_node(dev, -1); } -static struct kobject *virtual_device_parent(struct device *dev) +struct kobject *virtual_device_parent(struct device *dev) { static struct kobject *virtual_dir = NULL; diff --git a/include/linux/device.h b/include/linux/device.h index 9d6464ea99c6..ee10d4e7be1a 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -302,6 +302,8 @@ void subsys_interface_unregister(struct subsys_interface *sif); int subsys_system_register(struct bus_type *subsys, const struct attribute_group **groups); +int subsys_virtual_register(struct bus_type *subsys, + const struct attribute_group **groups); /** * struct class - device classes