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driver core: class.c: convert to only use class_to_subsys
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Now that class_to_subsys() can be used to get access to the internal
class private pointer, convert the remaining few places in class.c that
were accessing the pointer directly to use class_to_subsys() instead.

By doing this, the need for class_get() and class_put() goes away as no
one actually tries to increment the class structures anymore, only the
internal dynamic one.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230325194234.46588-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Greg Kroah-Hartman committed Mar 29, 2023
1 parent 884f8ce commit 7b884b7
Showing 1 changed file with 61 additions and 52 deletions.
113 changes: 61 additions & 52 deletions drivers/base/class.c
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Original file line number Diff line number Diff line change
Expand Up @@ -66,24 +66,6 @@ static struct subsys_private *class_to_subsys(const struct class *class)
return sp;
}

static const struct class *class_get(const struct class *class)
{
struct subsys_private *sp = class_to_subsys(class);

if (sp)
return class;
return NULL;
}

static void class_put(const struct class *class)
{
struct subsys_private *sp = class_to_subsys(class);

/* two puts are required as the call to bus_to_subsys incremented it again */
subsys_put(sp);
subsys_put(sp);
}

static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
char *buf)
{
Expand Down Expand Up @@ -148,22 +130,29 @@ static const struct kobj_type class_ktype = {
int class_create_file_ns(const struct class *cls, const struct class_attribute *attr,
const void *ns)
{
struct subsys_private *sp = class_to_subsys(cls);
int error;

if (cls)
error = sysfs_create_file_ns(&cls->p->subsys.kobj,
&attr->attr, ns);
else
error = -EINVAL;
if (!sp)
return -EINVAL;

error = sysfs_create_file_ns(&sp->subsys.kobj, &attr->attr, ns);
subsys_put(sp);

return error;
}
EXPORT_SYMBOL_GPL(class_create_file_ns);

void class_remove_file_ns(const struct class *cls, const struct class_attribute *attr,
const void *ns)
{
if (cls)
sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns);
struct subsys_private *sp = class_to_subsys(cls);

if (!sp)
return;

sysfs_remove_file_ns(&sp->subsys.kobj, &attr->attr, ns);
subsys_put(sp);
}
EXPORT_SYMBOL_GPL(class_remove_file_ns);

Expand All @@ -187,18 +176,6 @@ static void klist_class_dev_put(struct klist_node *n)
put_device(dev);
}

static int class_add_groups(const struct class *cls,
const struct attribute_group **groups)
{
return sysfs_create_groups(&cls->p->subsys.kobj, groups);
}

static void class_remove_groups(const struct class *cls,
const struct attribute_group **groups)
{
return sysfs_remove_groups(&cls->p->subsys.kobj, groups);
}

int class_register(struct class *cls)
{
struct subsys_private *cp;
Expand Down Expand Up @@ -235,8 +212,7 @@ int class_register(struct class *cls)
if (error)
goto err_out;

error = class_add_groups(class_get(cls), cls->class_groups);
class_put(cls);
error = sysfs_create_groups(&cp->subsys.kobj, cls->class_groups);
if (error) {
kobject_del(&cp->subsys.kobj);
kfree_const(cp->subsys.kobj.name);
Expand All @@ -253,9 +229,16 @@ EXPORT_SYMBOL_GPL(class_register);

void class_unregister(const struct class *cls)
{
struct subsys_private *sp = class_to_subsys(cls);

if (!sp)
return;

pr_debug("device class '%s': unregistering\n", cls->name);
class_remove_groups(cls, cls->class_groups);
kset_unregister(&cls->p->subsys);

sysfs_remove_groups(&sp->subsys.kobj, cls->class_groups);
kset_unregister(&sp->subsys);
subsys_put(sp);
}
EXPORT_SYMBOL_GPL(class_unregister);

Expand Down Expand Up @@ -334,11 +317,15 @@ EXPORT_SYMBOL_GPL(class_destroy);
void class_dev_iter_init(struct class_dev_iter *iter, const struct class *class,
const struct device *start, const struct device_type *type)
{
struct subsys_private *sp = class_to_subsys(class);
struct klist_node *start_knode = NULL;

if (!sp)
return;

if (start)
start_knode = &start->p->knode_class;
klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
iter->type = type;
}
EXPORT_SYMBOL_GPL(class_dev_iter_init);
Expand Down Expand Up @@ -405,13 +392,14 @@ EXPORT_SYMBOL_GPL(class_dev_iter_exit);
int class_for_each_device(const struct class *class, const struct device *start,
void *data, int (*fn)(struct device *, void *))
{
struct subsys_private *sp = class_to_subsys(class);
struct class_dev_iter iter;
struct device *dev;
int error = 0;

if (!class)
return -EINVAL;
if (!class->p) {
if (!sp) {
WARN(1, "%s called for class '%s' before it was initialized",
__func__, class->name);
return -EINVAL;
Expand All @@ -424,6 +412,7 @@ int class_for_each_device(const struct class *class, const struct device *start,
break;
}
class_dev_iter_exit(&iter);
subsys_put(sp);

return error;
}
Expand Down Expand Up @@ -453,12 +442,13 @@ struct device *class_find_device(const struct class *class, const struct device
const void *data,
int (*match)(struct device *, const void *))
{
struct subsys_private *sp = class_to_subsys(class);
struct class_dev_iter iter;
struct device *dev;

if (!class)
return NULL;
if (!class->p) {
if (!sp) {
WARN(1, "%s called for class '%s' before it was initialized",
__func__, class->name);
return NULL;
Expand All @@ -472,58 +462,77 @@ struct device *class_find_device(const struct class *class, const struct device
}
}
class_dev_iter_exit(&iter);
subsys_put(sp);

return dev;
}
EXPORT_SYMBOL_GPL(class_find_device);

int class_interface_register(struct class_interface *class_intf)
{
struct subsys_private *sp;
const struct class *parent;
struct class_dev_iter iter;
struct device *dev;

if (!class_intf || !class_intf->class)
return -ENODEV;

parent = class_get(class_intf->class);
if (!parent)
parent = class_intf->class;
sp = class_to_subsys(parent);
if (!sp)
return -EINVAL;

mutex_lock(&parent->p->mutex);
list_add_tail(&class_intf->node, &parent->p->interfaces);
/*
* Reference in sp is now incremented and will be dropped when
* the interface is removed in the call to class_interface_unregister()
*/

mutex_lock(&sp->mutex);
list_add_tail(&class_intf->node, &sp->interfaces);
if (class_intf->add_dev) {
class_dev_iter_init(&iter, parent, NULL, NULL);
while ((dev = class_dev_iter_next(&iter)))
class_intf->add_dev(dev, class_intf);
class_dev_iter_exit(&iter);
}
mutex_unlock(&parent->p->mutex);
mutex_unlock(&sp->mutex);

return 0;
}
EXPORT_SYMBOL_GPL(class_interface_register);

void class_interface_unregister(struct class_interface *class_intf)
{
struct subsys_private *sp;
struct class *parent = class_intf->class;
struct class_dev_iter iter;
struct device *dev;

if (!parent)
return;

mutex_lock(&parent->p->mutex);
sp = class_to_subsys(parent);
if (!sp)
return;

mutex_lock(&sp->mutex);
list_del_init(&class_intf->node);
if (class_intf->remove_dev) {
class_dev_iter_init(&iter, parent, NULL, NULL);
while ((dev = class_dev_iter_next(&iter)))
class_intf->remove_dev(dev, class_intf);
class_dev_iter_exit(&iter);
}
mutex_unlock(&parent->p->mutex);
mutex_unlock(&sp->mutex);

class_put(parent);
/*
* Decrement the reference count twice, once for the class_to_subsys()
* call in the start of this function, and the second one from the
* reference increment in class_interface_register()
*/
subsys_put(sp);
subsys_put(sp);
}
EXPORT_SYMBOL_GPL(class_interface_unregister);

Expand Down

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