diff options
Diffstat (limited to 'Documentation/filesystems/configfs')
| -rw-r--r-- | Documentation/filesystems/configfs/Makefile | 3 | ||||
| -rw-r--r-- | Documentation/filesystems/configfs/configfs.txt | 92 | ||||
| -rw-r--r-- | Documentation/filesystems/configfs/configfs_example_explicit.c (renamed from Documentation/filesystems/configfs/configfs_example.c) | 57 | ||||
| -rw-r--r-- | Documentation/filesystems/configfs/configfs_example_macros.c | 446 |
4 files changed, 553 insertions, 45 deletions
diff --git a/Documentation/filesystems/configfs/Makefile b/Documentation/filesystems/configfs/Makefile new file mode 100644 index 00000000000..be7ec5e67db --- /dev/null +++ b/Documentation/filesystems/configfs/Makefile @@ -0,0 +1,3 @@ +ifneq ($(CONFIG_CONFIGFS_FS),) +obj-m += configfs_example_explicit.o configfs_example_macros.o +endif diff --git a/Documentation/filesystems/configfs/configfs.txt b/Documentation/filesystems/configfs/configfs.txt index c4ff96b7c4e..b40fec9d3f5 100644 --- a/Documentation/filesystems/configfs/configfs.txt +++ b/Documentation/filesystems/configfs/configfs.txt @@ -1,5 +1,5 @@ -configfs - Userspace-driven kernel object configuation. +configfs - Userspace-driven kernel object configuration. Joel Becker <joel.becker@oracle.com> @@ -192,7 +192,7 @@ attribute value uses the store_attribute() method. struct configfs_attribute { char *ca_name; struct module *ca_owner; - mode_t ca_mode; + umode_t ca_mode; }; When a config_item wants an attribute to appear as a file in the item's @@ -209,7 +209,7 @@ will happen for write(2). [struct config_group] -A config_item cannot live in a vaccum. The only way one can be created +A config_item cannot live in a vacuum. The only way one can be created is via mkdir(2) on a config_group. This will trigger creation of a child item. @@ -238,6 +238,8 @@ config_item_type. struct config_group *(*make_group)(struct config_group *group, const char *name); int (*commit_item)(struct config_item *item); + void (*disconnect_notify)(struct config_group *group, + struct config_item *item); void (*drop_item)(struct config_group *group, struct config_item *item); }; @@ -254,7 +256,7 @@ using the group _init() functions on the group. Finally, when userspace calls rmdir(2) on the item or group, ct_group_ops->drop_item() is called. As a config_group is also a -config_item, it is not necessary for a seperate drop_group() method. +config_item, it is not necessary for a separate drop_group() method. The subsystem must config_item_put() the reference that was initialized upon item allocation. If a subsystem has no work to do, it may omit the ct_group_ops->drop_item() method, and configfs will call @@ -268,6 +270,16 @@ the item in other threads, the memory is safe. It may take some time for the item to actually disappear from the subsystem's usage. But it is gone from configfs. +When drop_item() is called, the item's linkage has already been torn +down. It no longer has a reference on its parent and has no place in +the item hierarchy. If a client needs to do some cleanup before this +teardown happens, the subsystem can implement the +ct_group_ops->disconnect_notify() method. The method is called after +configfs has removed the item from the filesystem view but before the +item is removed from its parent group. Like drop_item(), +disconnect_notify() is void and cannot fail. Client subsystems should +not drop any references here, as they still must do it in drop_item(). + A config_group cannot be removed while it still has child items. This is implemented in the configfs rmdir(2) code. ->drop_item() will not be called, as the item has not been dropped. rmdir(2) will fail, as the @@ -275,23 +287,23 @@ directory is not empty. [struct configfs_subsystem] -A subsystem must register itself, ususally at module_init time. This +A subsystem must register itself, usually at module_init time. This tells configfs to make the subsystem appear in the file tree. struct configfs_subsystem { struct config_group su_group; - struct semaphore su_sem; + struct mutex su_mutex; }; int configfs_register_subsystem(struct configfs_subsystem *subsys); void configfs_unregister_subsystem(struct configfs_subsystem *subsys); - A subsystem consists of a toplevel config_group and a semaphore. + A subsystem consists of a toplevel config_group and a mutex. The group is where child config_items are created. For a subsystem, this group is usually defined statically. Before calling configfs_register_subsystem(), the subsystem must have initialized the group via the usual group _init() functions, and it must also have -initialized the semaphore. +initialized the mutex. When the register call returns, the subsystem is live, and it will be visible via configfs. At that point, mkdir(2) can be called and the subsystem must be ready for it. @@ -299,11 +311,22 @@ the subsystem must be ready for it. [An Example] The best example of these basic concepts is the simple_children -subsystem/group and the simple_child item in configfs_example.c It -shows a trivial object displaying and storing an attribute, and a simple -group creating and destroying these children. - -[Hierarchy Navigation and the Subsystem Semaphore] +subsystem/group and the simple_child item in configfs_example_explicit.c +and configfs_example_macros.c. It shows a trivial object displaying and +storing an attribute, and a simple group creating and destroying these +children. + +The only difference between configfs_example_explicit.c and +configfs_example_macros.c is how the attributes of the childless item +are defined. The childless item has extended attributes, each with +their own show()/store() operation. This follows a convention commonly +used in sysfs. configfs_example_explicit.c creates these attributes +by explicitly defining the structures involved. Conversely +configfs_example_macros.c uses some convenience macros from configfs.h +to define the attributes. These macros are similar to their sysfs +counterparts. + +[Hierarchy Navigation and the Subsystem Mutex] There is an extra bonus that configfs provides. The config_groups and config_items are arranged in a hierarchy due to the fact that they @@ -314,19 +337,19 @@ and config_item->ci_parent structure members. A subsystem can navigate the cg_children list and the ci_parent pointer to see the tree created by the subsystem. This can race with configfs' -management of the hierarchy, so configfs uses the subsystem semaphore to +management of the hierarchy, so configfs uses the subsystem mutex to protect modifications. Whenever a subsystem wants to navigate the hierarchy, it must do so under the protection of the subsystem -semaphore. +mutex. -A subsystem will be prevented from acquiring the semaphore while a newly +A subsystem will be prevented from acquiring the mutex while a newly allocated item has not been linked into this hierarchy. Similarly, it -will not be able to acquire the semaphore while a dropping item has not +will not be able to acquire the mutex while a dropping item has not yet been unlinked. This means that an item's ci_parent pointer will never be NULL while the item is in configfs, and that an item will only be in its parent's cg_children list for the same duration. This allows a subsystem to trust ci_parent and cg_children while they hold the -semaphore. +mutex. [Item Aggregation Via symlink(2)] @@ -365,7 +388,7 @@ more explicit to have a method whereby userspace sees this divergence. Rather than have a group where some items behave differently than others, configfs provides a method whereby one or many subgroups are automatically created inside the parent at its creation. Thus, -mkdir("parent) results in "parent", "parent/subgroup1", up through +mkdir("parent") results in "parent", "parent/subgroup1", up through "parent/subgroupN". Items of type 1 can now be created in "parent/subgroup1", and items of type N can be created in "parent/subgroupN". @@ -386,6 +409,33 @@ As a consequence of this, default_groups cannot be removed directly via rmdir(2). They also are not considered when rmdir(2) on the parent group is checking for children. +[Dependent Subsystems] + +Sometimes other drivers depend on particular configfs items. For +example, ocfs2 mounts depend on a heartbeat region item. If that +region item is removed with rmdir(2), the ocfs2 mount must BUG or go +readonly. Not happy. + +configfs provides two additional API calls: configfs_depend_item() and +configfs_undepend_item(). A client driver can call +configfs_depend_item() on an existing item to tell configfs that it is +depended on. configfs will then return -EBUSY from rmdir(2) for that +item. When the item is no longer depended on, the client driver calls +configfs_undepend_item() on it. + +These API cannot be called underneath any configfs callbacks, as +they will conflict. They can block and allocate. A client driver +probably shouldn't calling them of its own gumption. Rather it should +be providing an API that external subsystems call. + +How does this work? Imagine the ocfs2 mount process. When it mounts, +it asks for a heartbeat region item. This is done via a call into the +heartbeat code. Inside the heartbeat code, the region item is looked +up. Here, the heartbeat code calls configfs_depend_item(). If it +succeeds, then heartbeat knows the region is safe to give to ocfs2. +If it fails, it was being torn down anyway, and heartbeat can gracefully +pass up an error. + [Committable Items] NOTE: Committable items are currently unimplemented. @@ -406,7 +456,7 @@ that condition is met. Far better would be an explicit action notifying the subsystem that the config_item is ready to go. More importantly, an explicit action allows -the subsystem to provide feedback as to whether the attibutes are +the subsystem to provide feedback as to whether the attributes are initialized in a way that makes sense. configfs provides this as committable items. @@ -422,7 +472,7 @@ support mkdir(2) or rmdir(2) either. It only allows rename(2). The "pending" directory does allow mkdir(2) and rmdir(2). An item is created in the "pending" directory. Its attributes can be modified at will. Userspace commits the item by renaming it into the "live" -directory. At this point, the subsystem recieves the ->commit_item() +directory. At this point, the subsystem receives the ->commit_item() callback. If all required attributes are filled to satisfaction, the method returns zero and the item is moved to the "live" directory. diff --git a/Documentation/filesystems/configfs/configfs_example.c b/Documentation/filesystems/configfs/configfs_example_explicit.c index f3c6e4946f9..1420233dfa5 100644 --- a/Documentation/filesystems/configfs/configfs_example.c +++ b/Documentation/filesystems/configfs/configfs_example_explicit.c @@ -1,8 +1,10 @@ /* * vim: noexpandtab ts=8 sts=0 sw=8: * - * configfs_example.c - This file is a demonstration module containing - * a number of configfs subsystems. + * configfs_example_explicit.c - This file is a demonstration module + * containing a number of configfs subsystems. It explicitly defines + * each structure without using the helper macros defined in + * configfs.h. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public @@ -87,7 +89,7 @@ static ssize_t childless_storeme_write(struct childless *childless, char *p = (char *) page; tmp = simple_strtoul(p, &p, 10); - if (!p || (*p && (*p != '\n'))) + if ((*p != '\0') && (*p != '\n')) return -EINVAL; if (tmp > INT_MAX) @@ -264,15 +266,22 @@ static struct config_item_type simple_child_type = { }; +struct simple_children { + struct config_group group; +}; + +static inline struct simple_children *to_simple_children(struct config_item *item) +{ + return item ? container_of(to_config_group(item), struct simple_children, group) : NULL; +} + static struct config_item *simple_children_make_item(struct config_group *group, const char *name) { struct simple_child *simple_child; - simple_child = kmalloc(sizeof(struct simple_child), GFP_KERNEL); + simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL); if (!simple_child) - return NULL; - - memset(simple_child, 0, sizeof(struct simple_child)); + return ERR_PTR(-ENOMEM); config_item_init_type_name(&simple_child->item, name, &simple_child_type); @@ -294,8 +303,8 @@ static struct configfs_attribute *simple_children_attrs[] = { }; static ssize_t simple_children_attr_show(struct config_item *item, - struct configfs_attribute *attr, - char *page) + struct configfs_attribute *attr, + char *page) { return sprintf(page, "[02-simple-children]\n" @@ -304,7 +313,13 @@ static ssize_t simple_children_attr_show(struct config_item *item, "items have only one attribute that is readable and writeable.\n"); } +static void simple_children_release(struct config_item *item) +{ + kfree(to_simple_children(item)); +} + static struct configfs_item_operations simple_children_item_ops = { + .release = simple_children_release, .show_attribute = simple_children_attr_show, }; @@ -320,6 +335,7 @@ static struct config_item_type simple_children_type = { .ct_item_ops = &simple_children_item_ops, .ct_group_ops = &simple_children_group_ops, .ct_attrs = simple_children_attrs, + .ct_owner = THIS_MODULE, }; static struct configfs_subsystem simple_children_subsys = { @@ -344,20 +360,14 @@ static struct configfs_subsystem simple_children_subsys = { * children of its own. */ -struct simple_children { - struct config_group group; -}; - static struct config_group *group_children_make_group(struct config_group *group, const char *name) { struct simple_children *simple_children; - simple_children = kmalloc(sizeof(struct simple_children), + simple_children = kzalloc(sizeof(struct simple_children), GFP_KERNEL); if (!simple_children) - return NULL; - - memset(simple_children, 0, sizeof(struct simple_children)); + return ERR_PTR(-ENOMEM); config_group_init_type_name(&simple_children->group, name, &simple_children_type); @@ -377,8 +387,8 @@ static struct configfs_attribute *group_children_attrs[] = { }; static ssize_t group_children_attr_show(struct config_item *item, - struct configfs_attribute *attr, - char *page) + struct configfs_attribute *attr, + char *page) { return sprintf(page, "[03-group-children]\n" @@ -403,6 +413,7 @@ static struct config_item_type group_children_type = { .ct_item_ops = &group_children_item_ops, .ct_group_ops = &group_children_group_ops, .ct_attrs = group_children_attrs, + .ct_owner = THIS_MODULE, }; static struct configfs_subsystem group_children_subsys = { @@ -440,7 +451,7 @@ static int __init configfs_example_init(void) subsys = example_subsys[i]; config_group_init(&subsys->su_group); - init_MUTEX(&subsys->su_sem); + mutex_init(&subsys->su_mutex); ret = configfs_register_subsystem(subsys); if (ret) { printk(KERN_ERR "Error %d while registering subsystem %s\n", @@ -453,9 +464,8 @@ static int __init configfs_example_init(void) return 0; out_unregister: - for (; i >= 0; i--) { + for (i--; i >= 0; i--) configfs_unregister_subsystem(example_subsys[i]); - } return ret; } @@ -464,9 +474,8 @@ static void __exit configfs_example_exit(void) { int i; - for (i = 0; example_subsys[i]; i++) { + for (i = 0; example_subsys[i]; i++) configfs_unregister_subsystem(example_subsys[i]); - } } module_init(configfs_example_init); diff --git a/Documentation/filesystems/configfs/configfs_example_macros.c b/Documentation/filesystems/configfs/configfs_example_macros.c new file mode 100644 index 00000000000..327dfbc640a --- /dev/null +++ b/Documentation/filesystems/configfs/configfs_example_macros.c @@ -0,0 +1,446 @@ +/* + * vim: noexpandtab ts=8 sts=0 sw=8: + * + * configfs_example_macros.c - This file is a demonstration module + * containing a number of configfs subsystems. It uses the helper + * macros defined by configfs.h + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + * + * Based on sysfs: + * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel + * + * configfs Copyright (C) 2005 Oracle. All rights reserved. + */ + +#include <linux/init.h> +#include <linux/module.h> +#include <linux/slab.h> + +#include <linux/configfs.h> + + + +/* + * 01-childless + * + * This first example is a childless subsystem. It cannot create + * any config_items. It just has attributes. + * + * Note that we are enclosing the configfs_subsystem inside a container. + * This is not necessary if a subsystem has no attributes directly + * on the subsystem. See the next example, 02-simple-children, for + * such a subsystem. + */ + +struct childless { + struct configfs_subsystem subsys; + int showme; + int storeme; +}; + +static inline struct childless *to_childless(struct config_item *item) +{ + return item ? container_of(to_configfs_subsystem(to_config_group(item)), struct childless, subsys) : NULL; +} + +CONFIGFS_ATTR_STRUCT(childless); +#define CHILDLESS_ATTR(_name, _mode, _show, _store) \ +struct childless_attribute childless_attr_##_name = __CONFIGFS_ATTR(_name, _mode, _show, _store) +#define CHILDLESS_ATTR_RO(_name, _show) \ +struct childless_attribute childless_attr_##_name = __CONFIGFS_ATTR_RO(_name, _show); + +static ssize_t childless_showme_read(struct childless *childless, + char *page) +{ + ssize_t pos; + + pos = sprintf(page, "%d\n", childless->showme); + childless->showme++; + + return pos; +} + +static ssize_t childless_storeme_read(struct childless *childless, + char *page) +{ + return sprintf(page, "%d\n", childless->storeme); +} + +static ssize_t childless_storeme_write(struct childless *childless, + const char *page, + size_t count) +{ + unsigned long tmp; + char *p = (char *) page; + + tmp = simple_strtoul(p, &p, 10); + if (!p || (*p && (*p != '\n'))) + return -EINVAL; + + if (tmp > INT_MAX) + return -ERANGE; + + childless->storeme = tmp; + + return count; +} + +static ssize_t childless_description_read(struct childless *childless, + char *page) +{ + return sprintf(page, +"[01-childless]\n" +"\n" +"The childless subsystem is the simplest possible subsystem in\n" +"configfs. It does not support the creation of child config_items.\n" +"It only has a few attributes. In fact, it isn't much different\n" +"than a directory in /proc.\n"); +} + +CHILDLESS_ATTR_RO(showme, childless_showme_read); +CHILDLESS_ATTR(storeme, S_IRUGO | S_IWUSR, childless_storeme_read, + childless_storeme_write); +CHILDLESS_ATTR_RO(description, childless_description_read); + +static struct configfs_attribute *childless_attrs[] = { + &childless_attr_showme.attr, + &childless_attr_storeme.attr, + &childless_attr_description.attr, + NULL, +}; + +CONFIGFS_ATTR_OPS(childless); +static struct configfs_item_operations childless_item_ops = { + .show_attribute = childless_attr_show, + .store_attribute = childless_attr_store, +}; + +static struct config_item_type childless_type = { + .ct_item_ops = &childless_item_ops, + .ct_attrs = childless_attrs, + .ct_owner = THIS_MODULE, +}; + +static struct childless childless_subsys = { + .subsys = { + .su_group = { + .cg_item = { + .ci_namebuf = "01-childless", + .ci_type = &childless_type, + }, + }, + }, +}; + + +/* ----------------------------------------------------------------- */ + +/* + * 02-simple-children + * + * This example merely has a simple one-attribute child. Note that + * there is no extra attribute structure, as the child's attribute is + * known from the get-go. Also, there is no container for the + * subsystem, as it has no attributes of its own. + */ + +struct simple_child { + struct config_item item; + int storeme; +}; + +static inline struct simple_child *to_simple_child(struct config_item *item) +{ + return item ? container_of(item, struct simple_child, item) : NULL; +} + +static struct configfs_attribute simple_child_attr_storeme = { + .ca_owner = THIS_MODULE, + .ca_name = "storeme", + .ca_mode = S_IRUGO | S_IWUSR, +}; + +static struct configfs_attribute *simple_child_attrs[] = { + &simple_child_attr_storeme, + NULL, +}; + +static ssize_t simple_child_attr_show(struct config_item *item, + struct configfs_attribute *attr, + char *page) +{ + ssize_t count; + struct simple_child *simple_child = to_simple_child(item); + + count = sprintf(page, "%d\n", simple_child->storeme); + + return count; +} + +static ssize_t simple_child_attr_store(struct config_item *item, + struct configfs_attribute *attr, + const char *page, size_t count) +{ + struct simple_child *simple_child = to_simple_child(item); + unsigned long tmp; + char *p = (char *) page; + + tmp = simple_strtoul(p, &p, 10); + if (!p || (*p && (*p != '\n'))) + return -EINVAL; + + if (tmp > INT_MAX) + return -ERANGE; + + simple_child->storeme = tmp; + + return count; +} + +static void simple_child_release(struct config_item *item) +{ + kfree(to_simple_child(item)); +} + +static struct configfs_item_operations simple_child_item_ops = { + .release = simple_child_release, + .show_attribute = simple_child_attr_show, + .store_attribute = simple_child_attr_store, +}; + +static struct config_item_type simple_child_type = { + .ct_item_ops = &simple_child_item_ops, + .ct_attrs = simple_child_attrs, + .ct_owner = THIS_MODULE, +}; + + +struct simple_children { + struct config_group group; +}; + +static inline struct simple_children *to_simple_children(struct config_item *item) +{ + return item ? container_of(to_config_group(item), struct simple_children, group) : NULL; +} + +static struct config_item *simple_children_make_item(struct config_group *group, const char *name) +{ + struct simple_child *simple_child; + + simple_child = kzalloc(sizeof(struct simple_child), GFP_KERNEL); + if (!simple_child) + return ERR_PTR(-ENOMEM); + + config_item_init_type_name(&simple_child->item, name, + &simple_child_type); + + simple_child->storeme = 0; + + return &simple_child->item; +} + +static struct configfs_attribute simple_children_attr_description = { + .ca_owner = THIS_MODULE, + .ca_name = "description", + .ca_mode = S_IRUGO, +}; + +static struct configfs_attribute *simple_children_attrs[] = { + &simple_children_attr_description, + NULL, +}; + +static ssize_t simple_children_attr_show(struct config_item *item, + struct configfs_attribute *attr, + char *page) +{ + return sprintf(page, +"[02-simple-children]\n" +"\n" +"This subsystem allows the creation of child config_items. These\n" +"items have only one attribute that is readable and writeable.\n"); +} + +static void simple_children_release(struct config_item *item) +{ + kfree(to_simple_children(item)); +} + +static struct configfs_item_operations simple_children_item_ops = { + .release = simple_children_release, + .show_attribute = simple_children_attr_show, +}; + +/* + * Note that, since no extra work is required on ->drop_item(), + * no ->drop_item() is provided. + */ +static struct configfs_group_operations simple_children_group_ops = { + .make_item = simple_children_make_item, +}; + +static struct config_item_type simple_children_type = { + .ct_item_ops = &simple_children_item_ops, + .ct_group_ops = &simple_children_group_ops, + .ct_attrs = simple_children_attrs, + .ct_owner = THIS_MODULE, +}; + +static struct configfs_subsystem simple_children_subsys = { + .su_group = { + .cg_item = { + .ci_namebuf = "02-simple-children", + .ci_type = &simple_children_type, + }, + }, +}; + + +/* ----------------------------------------------------------------- */ + +/* + * 03-group-children + * + * This example reuses the simple_children group from above. However, + * the simple_children group is not the subsystem itself, it is a + * child of the subsystem. Creation of a group in the subsystem creates + * a new simple_children group. That group can then have simple_child + * children of its own. + */ + +static struct config_group *group_children_make_group(struct config_group *group, const char *name) +{ + struct simple_children *simple_children; + + simple_children = kzalloc(sizeof(struct simple_children), + GFP_KERNEL); + if (!simple_children) + return ERR_PTR(-ENOMEM); + + config_group_init_type_name(&simple_children->group, name, + &simple_children_type); + + return &simple_children->group; +} + +static struct configfs_attribute group_children_attr_description = { + .ca_owner = THIS_MODULE, + .ca_name = "description", + .ca_mode = S_IRUGO, +}; + +static struct configfs_attribute *group_children_attrs[] = { + &group_children_attr_description, + NULL, +}; + +static ssize_t group_children_attr_show(struct config_item *item, + struct configfs_attribute *attr, + char *page) +{ + return sprintf(page, +"[03-group-children]\n" +"\n" +"This subsystem allows the creation of child config_groups. These\n" +"groups are like the subsystem simple-children.\n"); +} + +static struct configfs_item_operations group_children_item_ops = { + .show_attribute = group_children_attr_show, +}; + +/* + * Note that, since no extra work is required on ->drop_item(), + * no ->drop_item() is provided. + */ +static struct configfs_group_operations group_children_group_ops = { + .make_group = group_children_make_group, +}; + +static struct config_item_type group_children_type = { + .ct_item_ops = &group_children_item_ops, + .ct_group_ops = &group_children_group_ops, + .ct_attrs = group_children_attrs, + .ct_owner = THIS_MODULE, +}; + +static struct configfs_subsystem group_children_subsys = { + .su_group = { + .cg_item = { + .ci_namebuf = "03-group-children", + .ci_type = &group_children_type, + }, + }, +}; + +/* ----------------------------------------------------------------- */ + +/* + * We're now done with our subsystem definitions. + * For convenience in this module, here's a list of them all. It + * allows the init function to easily register them. Most modules + * will only have one subsystem, and will only call register_subsystem + * on it directly. + */ +static struct configfs_subsystem *example_subsys[] = { + &childless_subsys.subsys, + &simple_children_subsys, + &group_children_subsys, + NULL, +}; + +static int __init configfs_example_init(void) +{ + int ret; + int i; + struct configfs_subsystem *subsys; + + for (i = 0; example_subsys[i]; i++) { + subsys = example_subsys[i]; + + config_group_init(&subsys->su_group); + mutex_init(&subsys->su_mutex); + ret = configfs_register_subsystem(subsys); + if (ret) { + printk(KERN_ERR "Error %d while registering subsystem %s\n", + ret, + subsys->su_group.cg_item.ci_namebuf); + goto out_unregister; + } + } + + return 0; + +out_unregister: + for (i--; i >= 0; i--) + configfs_unregister_subsystem(example_subsys[i]); + + return ret; +} + +static void __exit configfs_example_exit(void) +{ + int i; + + for (i = 0; example_subsys[i]; i++) + configfs_unregister_subsystem(example_subsys[i]); +} + +module_init(configfs_example_init); +module_exit(configfs_example_exit); +MODULE_LICENSE("GPL"); |