[PATCH 02/46] driver core: fix namespace issue with devices assigned to classes

Greg Kroah-Hartman
2007-04-27T18:56:25Z

From: Kay Sievers <kay.sievers@vrfy.org>

- uses a kset in "struct class" to keep track of all directories
belonging to this class
- merges with the /sys/devices/virtual logic.
- removes the namespace-dir if the last member of that class
leaves the directory.

There may be locking or refcounting fixes left, I stopped when it seemed
to work with network and sound modules. :)

From: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/base/class.c | 2 +-
drivers/base/core.c | 82 +++++++++++++++++++++++++++++++++++++----------
include/linux/device.h | 3 +-
include/linux/kobject.h | 2 +
lib/kobject.c | 12 ++++++-
lib/kobject_uevent.c | 16 ++++++---
6 files changed, 89 insertions(+), 28 deletions(-)

diff --git a/drivers/base/class.c b/drivers/base/class.c
index d596812..80bbb20 100644
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -145,6 +145,7 @@ int class_register(struct class * cls)
INIT_LIST_HEAD(&cls->children);
INIT_LIST_HEAD(&cls->devices);
INIT_LIST_HEAD(&cls->interfaces);
+ kset_init(&cls->class_dirs);
init_MUTEX(&cls->sem);
error = kobject_set_name(&cls->subsys.kset.kobj, "%s", cls->name);
if (error)
@@ -163,7 +164,6 @@ int class_register(struct class * cls)
void class_unregister(struct class * cls)
{
pr_debug("device class '%s': unregistering\n", cls->name);
- kobject_unregister(cls->virtual_dir);
remove_class_attrs(cls);
subsystem_unregister(&cls->subsys);
}
diff --git a/drivers/base/core.c b/drivers/base/core.c
index db3a151..658eae5 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -477,34 +477,58 @@ static struct kobject * get_device_parent(struct device *dev,
return NULL;
}
#else
-static struct kobject * virtual_device_parent(struct device *dev)
+static struct kobject *virtual_device_parent(struct device *dev)
{
- if (!dev->class)
- return ERR_PTR(-ENODEV);
-
- if (!dev->class->virtual_dir) {
- static struct kobject *virtual_dir = NULL;
+ static struct kobject *virtual_dir = NULL;

- if (!virtual_dir)
- virtual_dir = kobject_add_dir(&devices_subsys.kset.kobj, "virtual");
- dev->class->virtual_dir = kobject_add_dir(virtual_dir, dev->class->name);
- }
+ if (!virtual_dir)
+ virtual_dir = kobject_add_dir(&devices_subsys.kset.kobj, "virtual");

- return dev->class->virtual_dir;
+ return virtual_dir;
}

static struct kobject * get_device_parent(struct device *dev,
struct device *parent)
{
- /* if this is a class device, and has no parent, create one */
- if ((dev->class) && (parent == NULL)) {
- return virtual_device_parent(dev);
- } else if (parent)
+ if (dev->class) {
+ struct kobject *kobj = NULL;
+ struct kobject *parent_kobj;
+ struct kobject *k;
+
+ /*
+ * If we have no parent, we live in "virtual".
+ * Class-devices with a bus-device as parent, live
+ * in a class-directory to prevent namespace collisions.
+ */
+ if (parent == NULL)
+ parent_kobj = virtual_device_parent(dev);
+ else if (parent->class)
+ return &parent->kobj;
+ else
+ parent_kobj = &parent->kobj;
+
+ /* find our class-directory at the parent and reference it */
+ spin_lock(&dev->class->class_dirs.list_lock);
+ list_for_each_entry(k, &dev->class->class_dirs.list, entry)
+ if (k->parent == parent_kobj) {
+ kobj = kobject_get(k);
+ break;
+ }
+ spin_unlock(&dev->class->class_dirs.list_lock);
+ if (kobj)
+ return kobj;
+
+ /* or create a new class-directory at the parent device */
+ return kobject_kset_add_dir(&dev->class->class_dirs,
+ parent_kobj, dev->class->name);
+ }
+
+ if (parent)
return &parent->kobj;
return NULL;
}
-
#endif
+
static int setup_parent(struct device *dev, struct device *parent)
{
struct kobject *kobj;
@@ -541,7 +565,6 @@ int device_add(struct device *dev)
pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);

parent = get_device(dev->parent);
-
error = setup_parent(dev, parent);
if (error)
goto Error;
@@ -787,6 +810,31 @@ void device_del(struct device * dev)
/* remove the device from the class list */
list_del_init(&dev->node);
up(&dev->class->sem);
+
+ /* If we live in a parent class-directory, unreference it */
+ if (dev->kobj.parent->kset == &dev->class->class_dirs) {
+ struct device *d;
+ int other = 0;
+
+ /*
+ * if we are the last child of our class, delete
+ * our class-directory at this parent
+ */
+ down(&dev->class->sem);
+ list_for_each_entry(d, &dev->class->devices, node) {
+ if (d == dev)
+ continue;
+ if (d->kobj.parent == dev->kobj.parent) {
+ other = 1;
+ break;
+ }
+ }
+ if (!other)
+ kobject_del(dev->kobj.parent);
+
+ kobject_put(dev->kobj.parent);
+ up(&dev->class->sem);
+ }
}
device_remove_file(dev, &dev->uevent_attr);
device_remove_groups(dev);
diff --git a/include/linux/device.h b/include/linux/device.h
index 5cf30e9..de0e73e 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -181,10 +181,9 @@ struct class {
struct list_head children;
struct list_head devices;
struct list_head interfaces;
+ struct kset class_dirs;
struct semaphore sem; /* locks both the children and interfaces lists */

- struct kobject *virtual_dir;
-
struct class_attribute * class_attrs;
struct class_device_attribute * class_dev_attrs;
struct device_attribute * dev_attrs;
diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index b850e03..d37cd7f 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -89,6 +89,8 @@ extern void kobject_unregister(struct kobject *);
extern struct kobject * kobject_get(struct kobject *);
extern void kobject_put(struct kobject *);

+extern struct kobject *kobject_kset_add_dir(struct kset *kset,
+ struct kobject *, const char *);
extern struct kobject *kobject_add_dir(struct kobject *, const char *);

extern char * kobject_get_path(struct kobject *, gfp_t);
diff --git a/lib/kobject.c b/lib/kobject.c
index 057921c..f664551 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -488,13 +488,15 @@ static struct kobj_type dir_ktype = {
};

/**
- * kobject_add_dir - add sub directory of object.
+ * kobject__kset_add_dir - add sub directory of object.
+ * @kset: kset the directory is belongs to.
* @parent: object in which a directory is created.
* @name: directory name.
*
* Add a plain directory object as child of given object.
*/
-struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
+struct kobject *kobject_kset_add_dir(struct kset *kset,
+ struct kobject *parent, const char *name)
{
struct kobject *k;
int ret;
@@ -506,6 +508,7 @@ struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
if (!k)
return NULL;

+ k->kset = kset;
k->parent = parent;
k->ktype = &dir_ktype;
kobject_set_name(k, name);
@@ -520,6 +523,11 @@ struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
return k;
}

+struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
+{
+ return kobject_kset_add_dir(NULL, parent, name);
+}
+
/**
* kset_init - initialize a kset for use
* @k: kset
diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index 82fc179..4122f38 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -115,6 +115,16 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
return 0;
}

+ /* originating subsystem */
+ if (uevent_ops && uevent_ops->name)
+ subsystem = uevent_ops->name(kset, kobj);
+ else
+ subsystem = kobject_name(&kset->kobj);
+ if (!subsystem) {
+ pr_debug("unset subsytem caused the event to drop!\n");
+ return 0;
+ }
+
/* environment index */
envp = kzalloc(NUM_ENVP * sizeof (char *), GFP_KERNEL);
if (!envp)
@@ -134,12 +144,6 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
goto exit;
}

- /* originating subsystem */
- if (uevent_ops && uevent_ops->name)
- subsystem = uevent_ops->name(kset, kobj);
- else
- subsystem = kobject_name(&kset->kobj);
-
/* event environemnt for helper process only */
envp[i++] = "HOME=/";
envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
--
1.5.1.2