diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-devices-online | 20 | ||||
| -rw-r--r-- | drivers/base/core.c | 130 | ||||
| -rw-r--r-- | include/linux/device.h | 21 |
3 files changed, 171 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-online b/Documentation/ABI/testing/sysfs-devices-online new file mode 100644 index 00000000000..f990026c074 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices-online @@ -0,0 +1,20 @@ +What: /sys/devices/.../online +Date: April 2013 +Contact: Rafael J. Wysocki <rafael.j.wysocki@intel.com> +Description: + The /sys/devices/.../online attribute is only present for + devices whose bus types provide .online() and .offline() + callbacks. The number read from it (0 or 1) reflects the value + of the device's 'offline' field. If that number is 1 and '0' + (or 'n', or 'N') is written to this file, the device bus type's + .offline() callback is executed for the device and (if + successful) its 'offline' field is updated accordingly. In + turn, if that number is 0 and '1' (or 'y', or 'Y') is written to + this file, the device bus type's .online() callback is executed + for the device and (if successful) its 'offline' field is + updated as appropriate. + + After a successful execution of the bus type's .offline() + callback the device cannot be used for any purpose until either + it is removed (i.e. device_del() is called for it), or its bus + type's .online() is exeucted successfully. diff --git a/drivers/base/core.c b/drivers/base/core.c index 01631243757..60c97568608 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -403,6 +403,36 @@ static ssize_t store_uevent(struct device *dev, struct device_attribute *attr, static struct device_attribute uevent_attr = __ATTR(uevent, S_IRUGO | S_IWUSR, show_uevent, store_uevent); +static ssize_t show_online(struct device *dev, struct device_attribute *attr, + char *buf) +{ + bool val; + + lock_device_hotplug(); + val = !dev->offline; + unlock_device_hotplug(); + return sprintf(buf, "%u\n", val); +} + +static ssize_t store_online(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + bool val; + int ret; + + ret = strtobool(buf, &val); + if (ret < 0) + return ret; + + lock_device_hotplug(); + ret = val ? device_online(dev) : device_offline(dev); + unlock_device_hotplug(); + return ret < 0 ? ret : count; +} + +static struct device_attribute online_attr = + __ATTR(online, S_IRUGO | S_IWUSR, show_online, store_online); + static int device_add_attributes(struct device *dev, struct device_attribute *attrs) { @@ -516,6 +546,12 @@ static int device_add_attrs(struct device *dev) if (error) goto err_remove_type_groups; + if (device_supports_offline(dev) && !dev->offline_disabled) { + error = device_create_file(dev, &online_attr); + if (error) + goto err_remove_type_groups; + } + return 0; err_remove_type_groups: @@ -536,6 +572,7 @@ static void device_remove_attrs(struct device *dev) struct class *class = dev->class; const struct device_type *type = dev->type; + device_remove_file(dev, &online_attr); device_remove_groups(dev, dev->groups); if (type) @@ -1431,6 +1468,99 @@ EXPORT_SYMBOL_GPL(put_device); EXPORT_SYMBOL_GPL(device_create_file); EXPORT_SYMBOL_GPL(device_remove_file); +static DEFINE_MUTEX(device_hotplug_lock); + +void lock_device_hotplug(void) +{ + mutex_lock(&device_hotplug_lock); +} + +void unlock_device_hotplug(void) +{ + mutex_unlock(&device_hotplug_lock); +} + +static int device_check_offline(struct device *dev, void *not_used) +{ + int ret; + + ret = device_for_each_child(dev, NULL, device_check_offline); + if (ret) + return ret; + + return device_supports_offline(dev) && !dev->offline ? -EBUSY : 0; +} + +/** + * device_offline - Prepare the device for hot-removal. + * @dev: Device to be put offline. + * + * Execute the device bus type's .offline() callback, if present, to prepare + * the device for a subsequent hot-removal. If that succeeds, the device must + * not be used until either it is removed or its bus type's .online() callback + * is executed. + * + * Call under device_hotplug_lock. + */ +int device_offline(struct device *dev) +{ + int ret; + + if (dev->offline_disabled) + return -EPERM; + + ret = device_for_each_child(dev, NULL, device_check_offline); + if (ret) + return ret; + + device_lock(dev); + if (device_supports_offline(dev)) { + if (dev->offline) { + ret = 1; + } else { + ret = dev->bus->offline(dev); + if (!ret) { + kobject_uevent(&dev->kobj, KOBJ_OFFLINE); + dev->offline = true; + } + } + } + device_unlock(dev); + + return ret; +} + +/** + * device_online - Put the device back online after successful device_offline(). + * @dev: Device to be put back online. + * + * If device_offline() has been successfully executed for @dev, but the device + * has not been removed subsequently, execute its bus type's .online() callback + * to indicate that the device can be used again. + * + * Call under device_hotplug_lock. + */ +int device_online(struct device *dev) +{ + int ret = 0; + + device_lock(dev); + if (device_supports_offline(dev)) { + if (dev->offline) { + ret = dev->bus->online(dev); + if (!ret) { + kobject_uevent(&dev->kobj, KOBJ_ONLINE); + dev->offline = false; + } + } else { + ret = 1; + } + } + device_unlock(dev); + + return ret; +} + struct root_device { struct device dev; struct module *owner; diff --git a/include/linux/device.h b/include/linux/device.h index c0a12612532..eeb33315514 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -71,6 +71,10 @@ extern void bus_remove_file(struct bus_type *, struct bus_attribute *); * the specific driver's probe to initial the matched device. * @remove: Called when a device removed from this bus. * @shutdown: Called at shut-down time to quiesce the device. + * + * @online: Called to put the device back online (after offlining it). + * @offline: Called to put the device offline for hot-removal. May fail. + * * @suspend: Called when a device on this bus wants to go to sleep mode. * @resume: Called to bring a device on this bus out of sleep mode. * @pm: Power management operations of this bus, callback the specific @@ -104,6 +108,9 @@ struct bus_type { int (*remove)(struct device *dev); void (*shutdown)(struct device *dev); + int (*online)(struct device *dev); + int (*offline)(struct device *dev); + int (*suspend)(struct device *dev, pm_message_t state); int (*resume)(struct device *dev); @@ -648,6 +655,8 @@ struct acpi_dev_node { * @release: Callback to free the device after all references have * gone away. This should be set by the allocator of the * device (i.e. the bus driver that discovered the device). + * @offline_disabled: If set, the device is permanently online. + * @offline: Set after successful invocation of bus type's .offline(). * * At the lowest level, every device in a Linux system is represented by an * instance of struct device. The device structure contains the information @@ -720,6 +729,9 @@ struct device { void (*release)(struct device *dev); struct iommu_group *iommu_group; + + bool offline_disabled:1; + bool offline:1; }; static inline struct device *kobj_to_dev(struct kobject *kobj) @@ -856,6 +868,15 @@ extern const char *device_get_devnode(struct device *dev, extern void *dev_get_drvdata(const struct device *dev); extern int dev_set_drvdata(struct device *dev, void *data); +static inline bool device_supports_offline(struct device *dev) +{ + return dev->bus && dev->bus->offline && dev->bus->online; +} + +extern void lock_device_hotplug(void); +extern void unlock_device_hotplug(void); +extern int device_offline(struct device *dev); +extern int device_online(struct device *dev); /* * Root device objects for grouping under /sys/devices */ |