From 4f3549d72d1b5c90ecc7e673402f38f4486d22c2 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 2 May 2013 22:15:29 +0200 Subject: Driver core: Add offline/online device operations In some cases, graceful hot-removal of devices is not possible, although in principle the devices in question support hotplug. For example, that may happen for the last CPU in the system or for memory modules holding kernel memory. In those cases it is nice to be able to check if the given device can be gracefully hot-removed before triggering a removal procedure that cannot be aborted or reversed. Unfortunately, however, the kernel currently doesn't provide any support for that. To address that deficiency, introduce support for offline and online operations that can be performed on devices, respectively, before a hot-removal and in case when it is necessary (or convenient) to put a device back online after a successful offline (that has not been followed by removal). The idea is that the offline will fail whenever the given device cannot be gracefully removed from the system and it will not be allowed to use the device after a successful offline (until a subsequent online) in analogy with the existing CPU offline/online mechanism. For now, the offline and online operations are introduced at the bus type level, as that should be sufficient for the most urgent use cases (CPUs and memory modules). In the future, however, the approach may be extended to cover some more complicated device offline/online scenarios involving device drivers etc. The lock_device_hotplug() and unlock_device_hotplug() functions are introduced because subsequent patches need to put larger pieces of code under device_hotplug_lock to prevent race conditions between device offline and removal from happening. Signed-off-by: Rafael J. Wysocki Acked-by: Greg Kroah-Hartman Reviewed-by: Toshi Kani --- include/linux/device.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index c0a126125325..eeb33315514c 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 */ -- cgit v1.2.3 From bfd63cd24df69120585c22e09fda78723772ee2a Mon Sep 17 00:00:00 2001 From: Michael Opdenacker Date: Wed, 26 Jun 2013 05:57:06 +0200 Subject: driver core: device.h: fix doc compilation warnings This patch fixes the below 3 warnings running "make htmldocs", by adding descriptions for recently added structure members: DOCPROC Documentation/DocBook/device-drivers.xml Warning(/work/git.free-electrons.com/users/michael-opdenacker/linux//include/linux/device.h:116): No description found for parameter 'lock_key' Warning(/work/git.free-electrons.com/users/michael-opdenacker/linux//include/linux/device.h:723): No description found for parameter 'cma_area' Warning(/work/git.free-electrons.com/users/michael-opdenacker/linux//include/linux/device.h:723): No description found for parameter 'iommu_group' Don't hesitate to propose better descriptions! Signed-off-by: Michael Opdenacker Signed-off-by: Greg Kroah-Hartman --- include/linux/device.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index c0a126125325..9d4835a8f8b8 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -80,6 +80,7 @@ extern void bus_remove_file(struct bus_type *, struct bus_attribute *); * bus-specific setup * @p: The private data of the driver core, only the driver core can * touch this. + * @lock_key: Lock class key for use by the lock validator * * A bus is a channel between the processor and one or more devices. For the * purposes of the device model, all devices are connected via a bus, even if @@ -635,6 +636,7 @@ struct acpi_dev_node { * segment limitations. * @dma_pools: Dma pools (if dma'ble device). * @dma_mem: Internal for coherent mem override. + * @cma_area: Contiguous memory area for dma allocations * @archdata: For arch-specific additions. * @of_node: Associated device tree node. * @acpi_node: Associated ACPI device node. @@ -648,6 +650,7 @@ 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). + * @iommu_group: IOMMU group the device belongs to. * * At the lowest level, every device in a Linux system is represented by an * instance of struct device. The device structure contains the information -- cgit v1.2.3 From ced321bf9151535f85779b0004c93529f860b2a4 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Sun, 14 Jul 2013 16:05:54 -0700 Subject: driver core: device.h: add RW and RO attribute macros Make it easier to create attributes without having to always audit the mode settings. Reviewed-by: Guenter Roeck Tested-by: Guenter Roeck Signed-off-by: Greg Kroah-Hartman --- include/linux/device.h | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index bcf8c0d4cd98..f207a8f49f80 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -47,7 +47,11 @@ struct bus_attribute { }; #define BUS_ATTR(_name, _mode, _show, _store) \ -struct bus_attribute bus_attr_##_name = __ATTR(_name, _mode, _show, _store) + struct bus_attribute bus_attr_##_name = __ATTR(_name, _mode, _show, _store) +#define BUS_ATTR_RW(_name) \ + struct bus_attribute bus_attr_##_name = __ATTR_RW(_name) +#define BUS_ATTR_RO(_name) \ + struct bus_attribute bus_attr_##_name = __ATTR_RO(_name) extern int __must_check bus_create_file(struct bus_type *, struct bus_attribute *); @@ -261,9 +265,12 @@ struct driver_attribute { size_t count); }; -#define DRIVER_ATTR(_name, _mode, _show, _store) \ -struct driver_attribute driver_attr_##_name = \ - __ATTR(_name, _mode, _show, _store) +#define DRIVER_ATTR(_name, _mode, _show, _store) \ + struct driver_attribute driver_attr_##_name = __ATTR(_name, _mode, _show, _store) +#define DRIVER_ATTR_RW(_name) \ + struct driver_attribute driver_attr_##_name = __ATTR_RW(_name) +#define DRIVER_ATTR_RO(_name) \ + struct driver_attribute driver_attr_##_name = __ATTR_RO(_name) extern int __must_check driver_create_file(struct device_driver *driver, const struct driver_attribute *attr); @@ -414,8 +421,12 @@ struct class_attribute { const struct class_attribute *attr); }; -#define CLASS_ATTR(_name, _mode, _show, _store) \ -struct class_attribute class_attr_##_name = __ATTR(_name, _mode, _show, _store) +#define CLASS_ATTR(_name, _mode, _show, _store) \ + struct class_attribute class_attr_##_name = __ATTR(_name, _mode, _show, _store) +#define CLASS_ATTR_RW(_name) \ + struct class_attribute class_attr_##_name = __ATTR_RW(_name) +#define CLASS_ATTR_RO(_name) \ + struct class_attribute class_attr_##_name = __ATTR_RO(_name) extern int __must_check class_create_file(struct class *class, const struct class_attribute *attr); @@ -423,7 +434,6 @@ extern void class_remove_file(struct class *class, const struct class_attribute *attr); /* Simple class attribute that is just a static string */ - struct class_attribute_string { struct class_attribute attr; char *str; @@ -512,6 +522,10 @@ ssize_t device_store_bool(struct device *dev, struct device_attribute *attr, #define DEVICE_ATTR(_name, _mode, _show, _store) \ struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store) +#define DEVICE_ATTR_RW(_name) \ + struct device_attribute dev_attr_##_name = __ATTR_RW(_name) +#define DEVICE_ATTR_RO(_name) \ + struct device_attribute dev_attr_##_name = __ATTR_RO(_name) #define DEVICE_ULONG_ATTR(_name, _mode, _var) \ struct dev_ext_attribute dev_attr_##_name = \ { __ATTR(_name, _mode, device_show_ulong, device_store_ulong), &(_var) } -- cgit v1.2.3 From 39ef311204941ddd01ea2950d6220c8ccc710d15 Mon Sep 17 00:00:00 2001 From: Guenter Roeck Date: Sun, 14 Jul 2013 16:05:57 -0700 Subject: driver core: Introduce device_create_groups device_create_groups lets callers create devices as well as associated sysfs attributes with a single call. This avoids race conditions seen if sysfs attributes on new devices are created later. [fixed up comment block placement and add checks for printk buffer formats - gregkh] Signed-off-by: Guenter Roeck Cc: Jean Delvare Signed-off-by: Greg Kroah-Hartman --- include/linux/device.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index f207a8f49f80..bd5931e89f74 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -938,6 +938,11 @@ extern __printf(5, 6) struct device *device_create(struct class *cls, struct device *parent, dev_t devt, void *drvdata, const char *fmt, ...); +extern __printf(6, 7) +struct device *device_create_with_groups(struct class *cls, + struct device *parent, dev_t devt, void *drvdata, + const struct attribute_group **groups, + const char *fmt, ...); extern void device_destroy(struct class *cls, dev_t devt); /* -- cgit v1.2.3 From d05a6f96c76062b5f25858ac02cf677602076f7e Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Sun, 14 Jul 2013 16:05:58 -0700 Subject: driver core: add default groups to struct class We should be using groups, not attribute lists, for classes to allow subdirectories, and soon, binary files. Groups are just more flexible overall, so add them. The dev_attrs list will go away after all in-kernel users are converted to use dev_groups. Reviewed-by: Guenter Roeck Tested-by: Guenter Roeck Signed-off-by: Greg Kroah-Hartman --- include/linux/device.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/linux/device.h') diff --git a/include/linux/device.h b/include/linux/device.h index bd5931e89f74..22b546a58591 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -320,6 +320,7 @@ int subsys_virtual_register(struct bus_type *subsys, * @name: Name of the class. * @owner: The module owner. * @class_attrs: Default attributes of this class. + * @dev_groups: Default attributes of the devices that belong to the class. * @dev_attrs: Default attributes of the devices belong to the class. * @dev_bin_attrs: Default binary attributes of the devices belong to the class. * @dev_kobj: The kobject that represents this class and links it into the hierarchy. @@ -349,7 +350,8 @@ struct class { struct module *owner; struct class_attribute *class_attrs; - struct device_attribute *dev_attrs; + struct device_attribute *dev_attrs; /* use dev_groups instead */ + const struct attribute_group **dev_groups; struct bin_attribute *dev_bin_attrs; struct kobject *dev_kobj; -- cgit v1.2.3