drivers/vfio/device_cdev.c | 8 +------- drivers/vfio/vfio.h | 4 ++-- drivers/vfio/vfio_main.c | 27 ++++++++++++++++----------- 3 files changed, 19 insertions(+), 20 deletions(-)
The class_create() call has been deprecated in favor of class_register()
as the driver core now allows for a struct class to be in read-only
memory. Replace vfio->device_class with a const struct class and drop
the class_create() call.
Compile tested with both CONFIG_VFIO_DEVICE_CDEV on and off (and
CONFIG_VFIO on); found no errors/warns in dmesg.
Link: https://lore.kernel.org/all/2023040244-duffel-pushpin-f738@gregkh/
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
---
drivers/vfio/device_cdev.c | 8 +-------
drivers/vfio/vfio.h | 4 ++--
drivers/vfio/vfio_main.c | 27 ++++++++++++++++-----------
3 files changed, 19 insertions(+), 20 deletions(-)
diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
index 8ceca24ac136..f926685a371d 100644
--- a/drivers/vfio/device_cdev.c
+++ b/drivers/vfio/device_cdev.c
@@ -293,14 +293,8 @@ int vfio_df_ioctl_detach_pt(struct vfio_device_file *df,
return 0;
}
-static char *vfio_device_devnode(const struct device *dev, umode_t *mode)
+int vfio_cdev_init(const struct class *device_class)
{
- return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev));
-}
-
-int vfio_cdev_init(struct class *device_class)
-{
- device_class->devnode = vfio_device_devnode;
return alloc_chrdev_region(&device_devt, 0,
MINORMASK + 1, "vfio-dev");
}
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 50128da18bca..fdc918771b05 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -378,7 +378,7 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep);
long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
struct vfio_device_bind_iommufd __user *arg);
void vfio_df_unbind_iommufd(struct vfio_device_file *df);
-int vfio_cdev_init(struct class *device_class);
+int vfio_cdev_init(const struct class *device_class);
void vfio_cdev_cleanup(void);
#else
static inline void vfio_init_device_cdev(struct vfio_device *device)
@@ -411,7 +411,7 @@ static inline void vfio_df_unbind_iommufd(struct vfio_device_file *df)
{
}
-static inline int vfio_cdev_init(struct class *device_class)
+static inline int vfio_cdev_init(const struct class *device_class)
{
return 0;
}
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 742477546b15..eecf8a1a5237 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -49,7 +49,6 @@
#define VFIO_MAGIC 0x5646494f /* "VFIO" */
static struct vfio {
- struct class *device_class;
struct ida device_ida;
struct vfsmount *vfs_mount;
int fs_count;
@@ -64,6 +63,16 @@ MODULE_PARM_DESC(enable_unsafe_noiommu_mode, "Enable UNSAFE, no-IOMMU mode. Thi
static DEFINE_XARRAY(vfio_device_set_xa);
+static char *vfio_device_devnode(const struct device *dev, umode_t *mode)
+{
+ return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev));
+}
+
+static const struct class vfio_device_class = {
+ .name = "vfio-dev",
+ .devnode = vfio_device_devnode
+};
+
int vfio_assign_device_set(struct vfio_device *device, void *set_id)
{
unsigned long idx = (unsigned long)set_id;
@@ -299,7 +308,7 @@ static int vfio_init_device(struct vfio_device *device, struct device *dev,
device_initialize(&device->device);
device->device.release = vfio_device_release;
- device->device.class = vfio.device_class;
+ device->device.class = &vfio_device_class;
device->device.parent = device->dev;
return 0;
@@ -1783,13 +1792,11 @@ static int __init vfio_init(void)
goto err_virqfd;
/* /sys/class/vfio-dev/vfioX */
- vfio.device_class = class_create("vfio-dev");
- if (IS_ERR(vfio.device_class)) {
- ret = PTR_ERR(vfio.device_class);
+ ret = class_register(&vfio_device_class);
+ if (ret)
goto err_dev_class;
- }
- ret = vfio_cdev_init(vfio.device_class);
+ ret = vfio_cdev_init(&vfio_device_class);
if (ret)
goto err_alloc_dev_chrdev;
@@ -1798,8 +1805,7 @@ static int __init vfio_init(void)
return 0;
err_alloc_dev_chrdev:
- class_destroy(vfio.device_class);
- vfio.device_class = NULL;
+ class_unregister(&vfio_device_class);
err_dev_class:
vfio_virqfd_exit();
err_virqfd:
@@ -1812,8 +1818,7 @@ static void __exit vfio_cleanup(void)
vfio_debugfs_remove_root();
ida_destroy(&vfio.device_ida);
vfio_cdev_cleanup();
- class_destroy(vfio.device_class);
- vfio.device_class = NULL;
+ class_unregister(&vfio_device_class);
vfio_virqfd_exit();
vfio_group_cleanup();
xa_destroy(&vfio_device_set_xa);
base-commit: d466c332e106fe666d1e2f5a24d08e308bebbfa1
--
2.53.0On Fri, 6 Mar 2026 21:40:31 +0100
Jori Koolstra <jkoolstra@xs4all.nl> wrote:
> The class_create() call has been deprecated in favor of class_register()
> as the driver core now allows for a struct class to be in read-only
> memory. Replace vfio->device_class with a const struct class and drop
> the class_create() call.
>
> Compile tested with both CONFIG_VFIO_DEVICE_CDEV on and off (and
> CONFIG_VFIO on); found no errors/warns in dmesg.
>
> Link: https://lore.kernel.org/all/2023040244-duffel-pushpin-f738@gregkh/
>
> Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Jori Koolstra <jkoolstra@xs4all.nl>
> ---
> drivers/vfio/device_cdev.c | 8 +-------
> drivers/vfio/vfio.h | 4 ++--
> drivers/vfio/vfio_main.c | 27 ++++++++++++++++-----------
> 3 files changed, 19 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
> index 8ceca24ac136..f926685a371d 100644
> --- a/drivers/vfio/device_cdev.c
> +++ b/drivers/vfio/device_cdev.c
> @@ -293,14 +293,8 @@ int vfio_df_ioctl_detach_pt(struct vfio_device_file *df,
> return 0;
> }
>
> -static char *vfio_device_devnode(const struct device *dev, umode_t *mode)
> +int vfio_cdev_init(const struct class *device_class)
> {
> - return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev));
> -}
> -
> -int vfio_cdev_init(struct class *device_class)
> -{
> - device_class->devnode = vfio_device_devnode;
device_class is no longer used in the function, we should drop the
parameter rather than change it to a const. Thanks,
Alex
> return alloc_chrdev_region(&device_devt, 0,
> MINORMASK + 1, "vfio-dev");
> }
> diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
> index 50128da18bca..fdc918771b05 100644
> --- a/drivers/vfio/vfio.h
> +++ b/drivers/vfio/vfio.h
> @@ -378,7 +378,7 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep);
> long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
> struct vfio_device_bind_iommufd __user *arg);
> void vfio_df_unbind_iommufd(struct vfio_device_file *df);
> -int vfio_cdev_init(struct class *device_class);
> +int vfio_cdev_init(const struct class *device_class);
> void vfio_cdev_cleanup(void);
> #else
> static inline void vfio_init_device_cdev(struct vfio_device *device)
> @@ -411,7 +411,7 @@ static inline void vfio_df_unbind_iommufd(struct vfio_device_file *df)
> {
> }
>
> -static inline int vfio_cdev_init(struct class *device_class)
> +static inline int vfio_cdev_init(const struct class *device_class)
> {
> return 0;
> }
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index 742477546b15..eecf8a1a5237 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -49,7 +49,6 @@
> #define VFIO_MAGIC 0x5646494f /* "VFIO" */
>
> static struct vfio {
> - struct class *device_class;
> struct ida device_ida;
> struct vfsmount *vfs_mount;
> int fs_count;
> @@ -64,6 +63,16 @@ MODULE_PARM_DESC(enable_unsafe_noiommu_mode, "Enable UNSAFE, no-IOMMU mode. Thi
>
> static DEFINE_XARRAY(vfio_device_set_xa);
>
> +static char *vfio_device_devnode(const struct device *dev, umode_t *mode)
> +{
> + return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev));
> +}
> +
> +static const struct class vfio_device_class = {
> + .name = "vfio-dev",
> + .devnode = vfio_device_devnode
> +};
> +
> int vfio_assign_device_set(struct vfio_device *device, void *set_id)
> {
> unsigned long idx = (unsigned long)set_id;
> @@ -299,7 +308,7 @@ static int vfio_init_device(struct vfio_device *device, struct device *dev,
>
> device_initialize(&device->device);
> device->device.release = vfio_device_release;
> - device->device.class = vfio.device_class;
> + device->device.class = &vfio_device_class;
> device->device.parent = device->dev;
> return 0;
>
> @@ -1783,13 +1792,11 @@ static int __init vfio_init(void)
> goto err_virqfd;
>
> /* /sys/class/vfio-dev/vfioX */
> - vfio.device_class = class_create("vfio-dev");
> - if (IS_ERR(vfio.device_class)) {
> - ret = PTR_ERR(vfio.device_class);
> + ret = class_register(&vfio_device_class);
> + if (ret)
> goto err_dev_class;
> - }
>
> - ret = vfio_cdev_init(vfio.device_class);
> + ret = vfio_cdev_init(&vfio_device_class);
> if (ret)
> goto err_alloc_dev_chrdev;
>
> @@ -1798,8 +1805,7 @@ static int __init vfio_init(void)
> return 0;
>
> err_alloc_dev_chrdev:
> - class_destroy(vfio.device_class);
> - vfio.device_class = NULL;
> + class_unregister(&vfio_device_class);
> err_dev_class:
> vfio_virqfd_exit();
> err_virqfd:
> @@ -1812,8 +1818,7 @@ static void __exit vfio_cleanup(void)
> vfio_debugfs_remove_root();
> ida_destroy(&vfio.device_ida);
> vfio_cdev_cleanup();
> - class_destroy(vfio.device_class);
> - vfio.device_class = NULL;
> + class_unregister(&vfio_device_class);
> vfio_virqfd_exit();
> vfio_group_cleanup();
> xa_destroy(&vfio_device_set_xa);
>
> base-commit: d466c332e106fe666d1e2f5a24d08e308bebbfa1
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