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Message-ID: <CAJZ5v0iczxyGP_11hS19D-zQnFgvdbDAhTbNC+ueNwNo9qi2fA@mail.gmail.com>
Date: Fri, 31 Mar 2023 12:26:34 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-kernel@...r.kernel.org,
"Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH 1/7] driver core: core: move to use class_to_subsys()
On Fri, Mar 31, 2023 at 11:33 AM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> There are a number of places in core.c that need access to the private
> subsystem structure of struct class, so move them to use
> class_to_subsys() instead of accessing it directly.
>
> This requires exporting class_to_subsys() out of class.c, but keeping it
> local to the driver core.
>
> Cc: "Rafael J. Wysocki" <rafael@...nel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Reviewed-by: Rafael J. Wysocki <rafael@...nel.org>
> ---
> drivers/base/base.h | 2 +
> drivers/base/class.c | 2 +-
> drivers/base/core.c | 121 ++++++++++++++++++++++++++++---------------
> 3 files changed, 81 insertions(+), 44 deletions(-)
>
> diff --git a/drivers/base/base.h b/drivers/base/base.h
> index 2867ca4ee4ce..6296164bb7f3 100644
> --- a/drivers/base/base.h
> +++ b/drivers/base/base.h
> @@ -73,6 +73,8 @@ static inline void subsys_put(struct subsys_private *sp)
> kset_put(&sp->subsys);
> }
>
> +struct subsys_private *class_to_subsys(const struct class *class);
> +
> struct driver_private {
> struct kobject kobj;
> struct klist klist_devices;
> diff --git a/drivers/base/class.c b/drivers/base/class.c
> index 1f12bd5d56d9..68a6f9b56d19 100644
> --- a/drivers/base/class.c
> +++ b/drivers/base/class.c
> @@ -39,7 +39,7 @@ static struct kset *class_kset;
> * NULL. A call to subsys_put() must be done when finished with the pointer in
> * order for it to be properly freed.
> */
> -static struct subsys_private *class_to_subsys(const struct class *class)
> +struct subsys_private *class_to_subsys(const struct class *class)
> {
> struct subsys_private *sp = NULL;
> struct kobject *kobj;
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 89249be22161..e3bc34fcf779 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -3149,8 +3149,8 @@ static const struct kobj_type class_dir_ktype = {
> .child_ns_type = class_dir_child_ns_type
> };
>
> -static struct kobject *
> -class_dir_create_and_add(const struct class *class, struct kobject *parent_kobj)
> +static struct kobject *class_dir_create_and_add(struct subsys_private *sp,
> + struct kobject *parent_kobj)
> {
> struct class_dir *dir;
> int retval;
> @@ -3159,12 +3159,12 @@ class_dir_create_and_add(const struct class *class, struct kobject *parent_kobj)
> if (!dir)
> return ERR_PTR(-ENOMEM);
>
> - dir->class = class;
> + dir->class = sp->class;
> kobject_init(&dir->kobj, &class_dir_ktype);
>
> - dir->kobj.kset = &class->p->glue_dirs;
> + dir->kobj.kset = &sp->glue_dirs;
>
> - retval = kobject_add(&dir->kobj, parent_kobj, "%s", class->name);
> + retval = kobject_add(&dir->kobj, parent_kobj, "%s", sp->class->name);
> if (retval < 0) {
> kobject_put(&dir->kobj);
> return ERR_PTR(retval);
> @@ -3177,9 +3177,10 @@ static DEFINE_MUTEX(gdp_mutex);
> static struct kobject *get_device_parent(struct device *dev,
> struct device *parent)
> {
> + struct subsys_private *sp = class_to_subsys(dev->class);
> struct kobject *kobj = NULL;
>
> - if (dev->class) {
> + if (sp) {
> struct kobject *parent_kobj;
> struct kobject *k;
>
> @@ -3190,30 +3191,34 @@ static struct kobject *get_device_parent(struct device *dev,
> */
> if (parent == NULL)
> parent_kobj = virtual_device_parent(dev);
> - else if (parent->class && !dev->class->ns_type)
> + else if (parent->class && !dev->class->ns_type) {
> + subsys_put(sp);
> return &parent->kobj;
> - else
> + } else {
> parent_kobj = &parent->kobj;
> + }
>
> mutex_lock(&gdp_mutex);
>
> /* find our class-directory at the parent and reference it */
> - spin_lock(&dev->class->p->glue_dirs.list_lock);
> - list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry)
> + spin_lock(&sp->glue_dirs.list_lock);
> + list_for_each_entry(k, &sp->glue_dirs.list, entry)
> if (k->parent == parent_kobj) {
> kobj = kobject_get(k);
> break;
> }
> - spin_unlock(&dev->class->p->glue_dirs.list_lock);
> + spin_unlock(&sp->glue_dirs.list_lock);
> if (kobj) {
> mutex_unlock(&gdp_mutex);
> + subsys_put(sp);
> return kobj;
> }
>
> /* or create a new class-directory at the parent device */
> - k = class_dir_create_and_add(dev->class, parent_kobj);
> + k = class_dir_create_and_add(sp, parent_kobj);
> /* do not emit an uevent for this simple "glue" directory */
> mutex_unlock(&gdp_mutex);
> + subsys_put(sp);
> return k;
> }
>
> @@ -3236,10 +3241,23 @@ static struct kobject *get_device_parent(struct device *dev,
> static inline bool live_in_glue_dir(struct kobject *kobj,
> struct device *dev)
> {
> - if (!kobj || !dev->class ||
> - kobj->kset != &dev->class->p->glue_dirs)
> + struct subsys_private *sp;
> + bool retval;
> +
> + if (!kobj || !dev->class)
> return false;
> - return true;
> +
> + sp = class_to_subsys(dev->class);
> + if (!sp)
> + return false;
> +
> + if (kobj->kset == &sp->glue_dirs)
> + retval = true;
> + else
> + retval = false;
> +
> + subsys_put(sp);
> + return retval;
> }
>
> static inline struct kobject *get_glue_dir(struct device *dev)
> @@ -3336,6 +3354,7 @@ static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
> static int device_add_class_symlinks(struct device *dev)
> {
> struct device_node *of_node = dev_of_node(dev);
> + struct subsys_private *sp;
> int error;
>
> if (of_node) {
> @@ -3345,12 +3364,11 @@ static int device_add_class_symlinks(struct device *dev)
> /* An error here doesn't warrant bringing down the device */
> }
>
> - if (!dev->class)
> + sp = class_to_subsys(dev->class);
> + if (!sp)
> return 0;
>
> - error = sysfs_create_link(&dev->kobj,
> - &dev->class->p->subsys.kobj,
> - "subsystem");
> + error = sysfs_create_link(&dev->kobj, &sp->subsys.kobj, "subsystem");
> if (error)
> goto out_devnode;
>
> @@ -3362,35 +3380,37 @@ static int device_add_class_symlinks(struct device *dev)
> }
>
> /* link in the class directory pointing to the device */
> - error = sysfs_create_link(&dev->class->p->subsys.kobj,
> - &dev->kobj, dev_name(dev));
> + error = sysfs_create_link(&sp->subsys.kobj, &dev->kobj, dev_name(dev));
> if (error)
> goto out_device;
> -
> - return 0;
> + goto exit;
>
> out_device:
> sysfs_remove_link(&dev->kobj, "device");
> -
> out_subsys:
> sysfs_remove_link(&dev->kobj, "subsystem");
> out_devnode:
> sysfs_remove_link(&dev->kobj, "of_node");
> +exit:
> + subsys_put(sp);
> return error;
> }
>
> static void device_remove_class_symlinks(struct device *dev)
> {
> + struct subsys_private *sp = class_to_subsys(dev->class);
> +
> if (dev_of_node(dev))
> sysfs_remove_link(&dev->kobj, "of_node");
>
> - if (!dev->class)
> + if (!sp)
> return;
>
> if (dev->parent && device_is_not_partition(dev))
> sysfs_remove_link(&dev->kobj, "device");
> sysfs_remove_link(&dev->kobj, "subsystem");
> - sysfs_delete_link(&dev->class->p->subsys.kobj, &dev->kobj, dev_name(dev));
> + sysfs_delete_link(&sp->subsys.kobj, &dev->kobj, dev_name(dev));
> + subsys_put(sp);
> }
>
> /**
> @@ -3499,6 +3519,7 @@ static int device_private_init(struct device *dev)
> */
> int device_add(struct device *dev)
> {
> + struct subsys_private *sp;
> struct device *parent;
> struct kobject *kobj;
> struct class_interface *class_intf;
> @@ -3627,18 +3648,18 @@ int device_add(struct device *dev)
> klist_add_tail(&dev->p->knode_parent,
> &parent->p->klist_children);
>
> - if (dev->class) {
> - mutex_lock(&dev->class->p->mutex);
> + sp = class_to_subsys(dev->class);
> + if (sp) {
> + mutex_lock(&sp->mutex);
> /* tie the class to the device */
> - klist_add_tail(&dev->p->knode_class,
> - &dev->class->p->klist_devices);
> + klist_add_tail(&dev->p->knode_class, &sp->klist_devices);
>
> /* notify any interfaces that the device is here */
> - list_for_each_entry(class_intf,
> - &dev->class->p->interfaces, node)
> + list_for_each_entry(class_intf, &sp->interfaces, node)
> if (class_intf->add_dev)
> class_intf->add_dev(dev, class_intf);
> - mutex_unlock(&dev->class->p->mutex);
> + mutex_unlock(&sp->mutex);
> + subsys_put(sp);
> }
> done:
> put_device(dev);
> @@ -3758,6 +3779,7 @@ EXPORT_SYMBOL_GPL(kill_device);
> */
> void device_del(struct device *dev)
> {
> + struct subsys_private *sp;
> struct device *parent = dev->parent;
> struct kobject *glue_dir = NULL;
> struct class_interface *class_intf;
> @@ -3784,18 +3806,20 @@ void device_del(struct device *dev)
> device_remove_sys_dev_entry(dev);
> device_remove_file(dev, &dev_attr_dev);
> }
> - if (dev->class) {
> +
> + sp = class_to_subsys(dev->class);
> + if (sp) {
> device_remove_class_symlinks(dev);
>
> - mutex_lock(&dev->class->p->mutex);
> + mutex_lock(&sp->mutex);
> /* notify any interfaces that the device is now gone */
> - list_for_each_entry(class_intf,
> - &dev->class->p->interfaces, node)
> + list_for_each_entry(class_intf, &sp->interfaces, node)
> if (class_intf->remove_dev)
> class_intf->remove_dev(dev, class_intf);
> /* remove the device from the class list */
> klist_del(&dev->p->knode_class);
> - mutex_unlock(&dev->class->p->mutex);
> + mutex_unlock(&sp->mutex);
> + subsys_put(sp);
> }
> device_remove_file(dev, &dev_attr_uevent);
> device_remove_attrs(dev);
> @@ -4458,9 +4482,16 @@ int device_rename(struct device *dev, const char *new_name)
> }
>
> if (dev->class) {
> - error = sysfs_rename_link_ns(&dev->class->p->subsys.kobj,
> - kobj, old_device_name,
> + struct subsys_private *sp = class_to_subsys(dev->class);
> +
> + if (!sp) {
> + error = -EINVAL;
> + goto out;
> + }
> +
> + error = sysfs_rename_link_ns(&sp->subsys.kobj, kobj, old_device_name,
> new_name, kobject_namespace(kobj));
> + subsys_put(sp);
> if (error)
> goto out;
> }
> @@ -4643,6 +4674,7 @@ int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
> {
> int error;
> struct kobject *kobj = &dev->kobj;
> + struct subsys_private *sp;
>
> dev = get_device(dev);
> if (!dev)
> @@ -4685,10 +4717,13 @@ int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
> * directory entry for @dev to @kuid/@...d. This ensures that the
> * symlink shows the same permissions as its target.
> */
> - error = sysfs_link_change_owner(&dev->class->p->subsys.kobj, &dev->kobj,
> - dev_name(dev), kuid, kgid);
> - if (error)
> + sp = class_to_subsys(dev->class);
> + if (!sp) {
> + error = -EINVAL;
> goto out;
> + }
> + error = sysfs_link_change_owner(&sp->subsys.kobj, &dev->kobj, dev_name(dev), kuid, kgid);
> + subsys_put(sp);
>
> out:
> put_device(dev);
> --
> 2.40.0
>
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