Re: [PATCH 2/6] mdev: introduce device specific ops

Jason Wang
2019-09-24T11:26:50Z

On 2019/9/24 上午6:59, Parav Pandit wrote:
>
>> -----Original Message-----
>> From: Jason Wang <jasowang@redhat.com>
>> Sent: Monday, September 23, 2019 8:03 AM
>> To: kvm@vger.kernel.org; linux-s390@vger.kernel.org; linux-
>> kernel@vger.kernel.org; dri-devel@lists.freedesktop.org; intel-
>> gfx@lists.freedesktop.org; intel-gvt-dev@lists.freedesktop.org;
>> kwankhede@nvidia.com; alex.williamson@redhat.com; mst@redhat.com;
>> tiwei.bie@intel.com
>> Cc: virtualization@lists.linux-foundation.org; netdev@vger.kernel.org;
>> cohuck@redhat.com; maxime.coquelin@redhat.com;
>> cunming.liang@intel.com; zhihong.wang@intel.com;
>> rob.miller@broadcom.com; xiao.w.wang@intel.com;
>> haotian.wang@sifive.com; zhenyuw@linux.intel.com; zhi.a.wang@intel.com;
>> jani.nikula@linux.intel.com; joonas.lahtinen@linux.intel.com;
>> rodrigo.vivi@intel.com; airlied@linux.ie; daniel@ffwll.ch;
>> farman@linux.ibm.com; pasic@linux.ibm.com; sebott@linux.ibm.com;
>> oberpar@linux.ibm.com; heiko.carstens@de.ibm.com; gor@linux.ibm.com;
>> borntraeger@de.ibm.com; akrowiak@linux.ibm.com; freude@linux.ibm.com;
>> lingshan.zhu@intel.com; Ido Shamay <idos@mellanox.com>;
>> eperezma@redhat.com; lulu@redhat.com; Parav Pandit
>> <parav@mellanox.com>; Jason Wang <jasowang@redhat.com>
>> Subject: [PATCH 2/6] mdev: introduce device specific ops
>>
>> Currently, except for the create and remove. The rest of mdev_parent_ops is
>> designed for vfio-mdev driver only and may not help for kernel mdev driver.
>> Follow the class id support by previous patch, this patch introduces device
>> specific ops pointer inside parent ops which points to device specific ops (e.g
>> vfio ops). This allows the future drivers like virtio-mdev to implement its own
>> device specific ops.
>>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>> .../driver-api/vfio-mediated-device.rst | 4 +-
>> MAINTAINERS | 1 +
>> drivers/gpu/drm/i915/gvt/kvmgt.c | 15 +++---
>> drivers/s390/cio/vfio_ccw_ops.c | 15 ++++--
>> drivers/s390/crypto/vfio_ap_ops.c | 11 ++--
>> drivers/vfio/mdev/vfio_mdev.c | 31 ++++++-----
>> include/linux/mdev.h | 36 ++-----------
>> include/linux/vfio_mdev.h | 53 +++++++++++++++++++
>> samples/vfio-mdev/mbochs.c | 17 +++---
>> samples/vfio-mdev/mdpy.c | 17 +++---
>> samples/vfio-mdev/mtty.c | 15 ++++--
>> 11 files changed, 138 insertions(+), 77 deletions(-) create mode 100644
>> include/linux/vfio_mdev.h
>>
>> diff --git a/Documentation/driver-api/vfio-mediated-device.rst
>> b/Documentation/driver-api/vfio-mediated-device.rst
>> index 0e052072e1d8..3ab00e48212f 100644
>> --- a/Documentation/driver-api/vfio-mediated-device.rst
>> +++ b/Documentation/driver-api/vfio-mediated-device.rst
>> @@ -152,7 +152,9 @@ callbacks per mdev parent device, per mdev type, or
>> any other categorization.
>> Vendor drivers are expected to be fully asynchronous in this respect or
>> provide their own internal resource protection.)
>>
>> -The callbacks in the mdev_parent_ops structure are as follows:
>> +The device specific callbacks are referred through device_ops pointer
>> +in mdev_parent_ops. For vfio-mdev device, its callbacks in device_ops
>> +are as follows:
>>
>> * open: open callback of mediated device
>> * close: close callback of mediated device diff --git a/MAINTAINERS
>> b/MAINTAINERS index b2326dece28e..89832b316500 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -17075,6 +17075,7 @@ S: Maintained
>> F: Documentation/driver-api/vfio-mediated-device.rst
>> F: drivers/vfio/mdev/
>> F: include/linux/mdev.h
>> +F: include/linux/vfio_mdev.h
>> F: samples/vfio-mdev/
>>
>> VFIO PLATFORM DRIVER
>> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c
>> b/drivers/gpu/drm/i915/gvt/kvmgt.c
>> index 19d51a35f019..8ea86b1e69f1 100644
>> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
>> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
>> @@ -42,6 +42,7 @@
>> #include <linux/kvm_host.h>
>> #include <linux/vfio.h>
>> #include <linux/mdev.h>
>> +#include <linux/vfio_mdev.h>
>> #include <linux/debugfs.h>
>>
>> #include <linux/nospec.h>
>> @@ -1600,20 +1601,22 @@ static const struct attribute_group
>> *intel_vgpu_groups[] = {
>> NULL,
>> };
>>
>> -static struct mdev_parent_ops intel_vgpu_ops = {
>> - .mdev_attr_groups = intel_vgpu_groups,
>> - .create = intel_vgpu_create,
>> - .remove = intel_vgpu_remove,
>> -
>> +static struct vfio_mdev_parent_ops intel_vfio_vgpu_ops = {
> Naming it with _dev prefix as intel_vfio_vgpu_dev_ops is better to differentiate with parent_ops.

Ok.

>> .open = intel_vgpu_open,
>> .release = intel_vgpu_release,
>> -
>> .read = intel_vgpu_read,
>> .write = intel_vgpu_write,
>> .mmap = intel_vgpu_mmap,
>> .ioctl = intel_vgpu_ioctl,
>> };
>>
>> +static struct mdev_parent_ops intel_vgpu_ops = {
>> + .mdev_attr_groups = intel_vgpu_groups,
>> + .create = intel_vgpu_create,
>> + .remove = intel_vgpu_remove,
>> + .device_ops = &intel_vfio_vgpu_ops,
>> +};
>> +
>> static int kvmgt_host_init(struct device *dev, void *gvt, const void *ops) {
>> struct attribute **kvm_type_attrs;
>> diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
>> index 246ff0f80944..02122bbc213e 100644
>> --- a/drivers/s390/cio/vfio_ccw_ops.c
>> +++ b/drivers/s390/cio/vfio_ccw_ops.c
>> @@ -12,6 +12,7 @@
>>
>> #include <linux/vfio.h>
>> #include <linux/mdev.h>
>> +#include <linux/vfio_mdev.h>
>> #include <linux/nospec.h>
>> #include <linux/slab.h>
>>
>> @@ -574,11 +575,7 @@ static ssize_t vfio_ccw_mdev_ioctl(struct
>> mdev_device *mdev,
>> }
>> }
>>
>> -static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
>> - .owner = THIS_MODULE,
>> - .supported_type_groups = mdev_type_groups,
>> - .create = vfio_ccw_mdev_create,
>> - .remove = vfio_ccw_mdev_remove,
>> +static const struct vfio_mdev_parent_ops vfio_mdev_ops = {
>> .open = vfio_ccw_mdev_open,
>> .release = vfio_ccw_mdev_release,
>> .read = vfio_ccw_mdev_read,
>> @@ -586,6 +583,14 @@ static const struct mdev_parent_ops
>> vfio_ccw_mdev_ops = {
>> .ioctl = vfio_ccw_mdev_ioctl,
>> };
>>
>> +static const struct mdev_parent_ops vfio_ccw_mdev_ops = {
>> + .owner = THIS_MODULE,
>> + .supported_type_groups = mdev_type_groups,
>> + .create = vfio_ccw_mdev_create,
>> + .remove = vfio_ccw_mdev_remove,
>> + .device_ops = &vfio_mdev_ops,
>> +};
>> +
>> int vfio_ccw_mdev_reg(struct subchannel *sch) {
>> return mdev_register_vfio_device(&sch->dev, &vfio_ccw_mdev_ops);
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
>> b/drivers/s390/crypto/vfio_ap_ops.c
>> index 7487fc39d2c5..4251becc7a6d 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -16,6 +16,7 @@
>> #include <linux/bitops.h>
>> #include <linux/kvm_host.h>
>> #include <linux/module.h>
>> +#include <linux/vfio_mdev.h>
>> #include <asm/kvm.h>
>> #include <asm/zcrypt.h>
>>
>> @@ -1280,15 +1281,19 @@ static ssize_t vfio_ap_mdev_ioctl(struct
>> mdev_device *mdev,
>> return ret;
>> }
>>
>> +static const struct vfio_mdev_parent_ops vfio_mdev_ops = {
>> + .open = vfio_ap_mdev_open,
>> + .release = vfio_ap_mdev_release,
>> + .ioctl = vfio_ap_mdev_ioctl,
>> +};
>> +
>> static const struct mdev_parent_ops vfio_ap_matrix_ops = {
>> .owner = THIS_MODULE,
>> .supported_type_groups = vfio_ap_mdev_type_groups,
>> .mdev_attr_groups = vfio_ap_mdev_attr_groups,
>> .create = vfio_ap_mdev_create,
>> .remove = vfio_ap_mdev_remove,
>> - .open = vfio_ap_mdev_open,
>> - .release = vfio_ap_mdev_release,
>> - .ioctl = vfio_ap_mdev_ioctl,
>> + .device_ops = &vfio_mdev_ops,
>> };
>>
>> int vfio_ap_mdev_register(void)
>> diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
>> index fd2a4d9a3f26..d23c9f58c84f 100644
>> --- a/drivers/vfio/mdev/vfio_mdev.c
>> +++ b/drivers/vfio/mdev/vfio_mdev.c
>> @@ -14,6 +14,7 @@
>> #include <linux/slab.h>
>> #include <linux/vfio.h>
>> #include <linux/mdev.h>
>> +#include <linux/vfio_mdev.h>
>>
>> #include "mdev_private.h"
>>
>> @@ -25,15 +26,16 @@ static int vfio_mdev_open(void *device_data) {
>> struct mdev_device *mdev = device_data;
>> struct mdev_parent *parent = mdev->parent;
>> + const struct vfio_mdev_parent_ops *ops = parent->ops->device_ops;
>> int ret;
>>
>> - if (unlikely(!parent->ops->open))
>> + if (unlikely(!ops->open))
>> return -EINVAL;
>>
> device_ops is optional and can be NULL for mdev devices which are not required to be mapped via vfio.
> So please change to,
>
> If (!ops || !ops->open)
> return -EINVAL;
>
> and rest of the below places.

My understanding is vfio_mdev can not talk to non vfio mdev device with
the help of class id.

Thanks

>
>> if (!try_module_get(THIS_MODULE))
>> return -ENODEV;
>>
>> - ret = parent->ops->open(mdev);
>> + ret = ops->open(mdev);
>> if (ret)
>> module_put(THIS_MODULE);
>>
>> @@ -44,9 +46,10 @@ static void vfio_mdev_release(void *device_data) {
>> struct mdev_device *mdev = device_data;
>> struct mdev_parent *parent = mdev->parent;
>> + const struct vfio_mdev_parent_ops *ops = parent->ops->device_ops;
>>
>> - if (likely(parent->ops->release))
>> - parent->ops->release(mdev);
>> + if (likely(ops->release))
>> + ops->release(mdev);
>>
>> module_put(THIS_MODULE);
>> }
>> @@ -56,11 +59,12 @@ static long vfio_mdev_unlocked_ioctl(void
>> *device_data, {
>> struct mdev_device *mdev = device_data;
>> struct mdev_parent *parent = mdev->parent;
>> + const struct vfio_mdev_parent_ops *ops = parent->ops->device_ops;
>>
>> - if (unlikely(!parent->ops->ioctl))
>> + if (unlikely(!ops->ioctl))
>> return -EINVAL;
>>
>> - return parent->ops->ioctl(mdev, cmd, arg);
>> + return ops->ioctl(mdev, cmd, arg);
>> }
>>
>> static ssize_t vfio_mdev_read(void *device_data, char __user *buf, @@ -68,11
>> +72,12 @@ static ssize_t vfio_mdev_read(void *device_data, char __user *buf,
>> {
>> struct mdev_device *mdev = device_data;
>> struct mdev_parent *parent = mdev->parent;
>> + const struct vfio_mdev_parent_ops *ops = parent->ops->device_ops;
>>
>> - if (unlikely(!parent->ops->read))
>> + if (unlikely(!ops->read))
>> return -EINVAL;
>>
>> - return parent->ops->read(mdev, buf, count, ppos);
>> + return ops->read(mdev, buf, count, ppos);
>> }
>>
>> static ssize_t vfio_mdev_write(void *device_data, const char __user *buf, @@
>> -80,22 +85,24 @@ static ssize_t vfio_mdev_write(void *device_data, const char
>> __user *buf, {
>> struct mdev_device *mdev = device_data;
>> struct mdev_parent *parent = mdev->parent;
>> + const struct vfio_mdev_parent_ops *ops = parent->ops->device_ops;
>>
>> - if (unlikely(!parent->ops->write))
>> + if (unlikely(!ops->write))
>> return -EINVAL;
>>
>> - return parent->ops->write(mdev, buf, count, ppos);
>> + return ops->write(mdev, buf, count, ppos);
>> }
>>
>> static int vfio_mdev_mmap(void *device_data, struct vm_area_struct *vma) {
>> struct mdev_device *mdev = device_data;
>> struct mdev_parent *parent = mdev->parent;
>> + const struct vfio_mdev_parent_ops *ops = parent->ops->device_ops;
>>
>> - if (unlikely(!parent->ops->mmap))
>> + if (unlikely(!ops->mmap))
>> return -EINVAL;
>>
>> - return parent->ops->mmap(mdev, vma);
>> + return ops->mmap(mdev, vma);
>> }
>>
>> static const struct vfio_device_ops vfio_mdev_dev_ops = { diff --git
>> a/include/linux/mdev.h b/include/linux/mdev.h index
>> 3ebae310f599..fa167bcb81e1 100644
>> --- a/include/linux/mdev.h
>> +++ b/include/linux/mdev.h
>> @@ -48,30 +48,8 @@ struct device *mdev_get_iommu_device(struct device
>> *dev);
>> * @mdev: mdev_device device structure which is being
>> * destroyed
>> * Returns integer: success (0) or error (< 0)
>> - * @open: Open mediated device.
>> - * @mdev: mediated device.
>> - * Returns integer: success (0) or error (< 0)
>> - * @release: release mediated device
>> - * @mdev: mediated device.
>> - * @read: Read emulation callback
>> - * @mdev: mediated device structure
>> - * @buf: read buffer
>> - * @count: number of bytes to read
>> - * @ppos: address.
>> - * Retuns number on bytes read on success or error.
>> - * @write: Write emulation callback
>> - * @mdev: mediated device structure
>> - * @buf: write buffer
>> - * @count: number of bytes to be written
>> - * @ppos: address.
>> - * Retuns number on bytes written on success or error.
>> - * @ioctl: IOCTL callback
>> - * @mdev: mediated device structure
>> - * @cmd: ioctl command
>> - * @arg: arguments to ioctl
>> - * @mmap: mmap callback
>> - * @mdev: mediated device structure
>> - * @vma: vma structure
>> + * @device_ops: Device specific emulation callback.
>> + *
>> * Parent device that support mediated device should be registered with mdev
>> * module with mdev_parent_ops structure.
>> **/
>> @@ -83,15 +61,7 @@ struct mdev_parent_ops {
>>
>> int (*create)(struct kobject *kobj, struct mdev_device *mdev);
>> int (*remove)(struct mdev_device *mdev);
>> - int (*open)(struct mdev_device *mdev);
>> - void (*release)(struct mdev_device *mdev);
>> - ssize_t (*read)(struct mdev_device *mdev, char __user *buf,
>> - size_t count, loff_t *ppos);
>> - ssize_t (*write)(struct mdev_device *mdev, const char __user *buf,
>> - size_t count, loff_t *ppos);
>> - long (*ioctl)(struct mdev_device *mdev, unsigned int cmd,
>> - unsigned long arg);
>> - int (*mmap)(struct mdev_device *mdev, struct vm_area_struct
>> *vma);
>> + const void *device_ops;
>> };
>>
>> /* interface for exporting mdev supported type attributes */ diff --git
>> a/include/linux/vfio_mdev.h b/include/linux/vfio_mdev.h new file mode
>> 100644 index 000000000000..0c1b34f98f5d
>> --- /dev/null
>> +++ b/include/linux/vfio_mdev.h
>> @@ -0,0 +1,53 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * VFIO Mediated device definition
>> + */
>> +
>> +#ifndef VFIO_MDEV_H
>> +#define VFIO_MDEV_H
>> +
>> +#include <linux/types.h>
>> +#include <linux/mdev.h>
>> +
>> +/**
>> + * struct vfio_mdev_parent_ops - Structure to be registered for each
>> + * parent device to register the device to vfio-mdev module.
>> + *
>> + * @open: Open mediated device.
>> + * @mdev: mediated device.
>> + * Returns integer: success (0) or error (< 0)
>> + * @release: release mediated device
>> + * @mdev: mediated device.
>> + * @read: Read emulation callback
>> + * @mdev: mediated device structure
>> + * @buf: read buffer
>> + * @count: number of bytes to read
>> + * @ppos: address.
>> + * Retuns number on bytes read on success or error.
>> + * @write: Write emulation callback
>> + * @mdev: mediated device structure
>> + * @buf: write buffer
>> + * @count: number of bytes to be written
>> + * @ppos: address.
>> + * Retuns number on bytes written on success or error.
>> + * @ioctl: IOCTL callback
>> + * @mdev: mediated device structure
>> + * @cmd: ioctl command
>> + * @arg: arguments to ioctl
>> + * @mmap: mmap callback
>> + * @mdev: mediated device structure
>> + * @vma: vma structure
>> + */
>> +struct vfio_mdev_parent_ops {
>> + int (*open)(struct mdev_device *mdev);
>> + void (*release)(struct mdev_device *mdev);
>> + ssize_t (*read)(struct mdev_device *mdev, char __user *buf,
>> + size_t count, loff_t *ppos);
>> + ssize_t (*write)(struct mdev_device *mdev, const char __user *buf,
>> + size_t count, loff_t *ppos);
>> + long (*ioctl)(struct mdev_device *mdev, unsigned int cmd,
>> + unsigned long arg);
>> + int (*mmap)(struct mdev_device *mdev, struct vm_area_struct
>> *vma);
>> +};
>> +
>> +#endif
>> diff --git a/samples/vfio-mdev/mbochs.c b/samples/vfio-mdev/mbochs.c index
>> 71a4469be85d..107cc30d0f45 100644
>> --- a/samples/vfio-mdev/mbochs.c
>> +++ b/samples/vfio-mdev/mbochs.c
>> @@ -30,6 +30,7 @@
>> #include <linux/iommu.h>
>> #include <linux/sysfs.h>
>> #include <linux/mdev.h>
>> +#include <linux/vfio_mdev.h>
>> #include <linux/pci.h>
>> #include <linux/dma-buf.h>
>> #include <linux/highmem.h>
>> @@ -1418,12 +1419,7 @@ static struct attribute_group *mdev_type_groups[]
>> = {
>> NULL,
>> };
>>
>> -static const struct mdev_parent_ops mdev_fops = {
>> - .owner = THIS_MODULE,
>> - .mdev_attr_groups = mdev_dev_groups,
>> - .supported_type_groups = mdev_type_groups,
>> - .create = mbochs_create,
>> - .remove = mbochs_remove,
>> +static const struct vfio_mdev_parent_ops vfio_mdev_ops = {
>> .open = mbochs_open,
>> .release = mbochs_close,
>> .read = mbochs_read,
>> @@ -1432,6 +1428,15 @@ static const struct mdev_parent_ops mdev_fops = {
>> .mmap = mbochs_mmap,
>> };
>>
>> +static const struct mdev_parent_ops mdev_fops = {
>> + .owner = THIS_MODULE,
>> + .mdev_attr_groups = mdev_dev_groups,
>> + .supported_type_groups = mdev_type_groups,
>> + .create = mbochs_create,
>> + .remove = mbochs_remove,
>> + .device_ops = &vfio_mdev_ops,
>> +};
>> +
>> static const struct file_operations vd_fops = {
>> .owner = THIS_MODULE,
>> };
>> diff --git a/samples/vfio-mdev/mdpy.c b/samples/vfio-mdev/mdpy.c index
>> d3029dd27d91..2cd2018a53f9 100644
>> --- a/samples/vfio-mdev/mdpy.c
>> +++ b/samples/vfio-mdev/mdpy.c
>> @@ -26,6 +26,7 @@
>> #include <linux/iommu.h>
>> #include <linux/sysfs.h>
>> #include <linux/mdev.h>
>> +#include <linux/vfio_mdev.h>
>> #include <linux/pci.h>
>> #include <drm/drm_fourcc.h>
>> #include "mdpy-defs.h"
>> @@ -725,12 +726,7 @@ static struct attribute_group *mdev_type_groups[] = {
>> NULL,
>> };
>>
>> -static const struct mdev_parent_ops mdev_fops = {
>> - .owner = THIS_MODULE,
>> - .mdev_attr_groups = mdev_dev_groups,
>> - .supported_type_groups = mdev_type_groups,
>> - .create = mdpy_create,
>> - .remove = mdpy_remove,
>> +static const struct vfio_mdev_parent_ops vfio_mdev_ops = {
>> .open = mdpy_open,
>> .release = mdpy_close,
>> .read = mdpy_read,
>> @@ -739,6 +735,15 @@ static const struct mdev_parent_ops mdev_fops = {
>> .mmap = mdpy_mmap,
>> };
>>
>> +static const struct mdev_parent_ops mdev_fops = {
>> + .owner = THIS_MODULE,
>> + .mdev_attr_groups = mdev_dev_groups,
>> + .supported_type_groups = mdev_type_groups,
>> + .create = mdpy_create,
>> + .remove = mdpy_remove,
>> + .device_ops = &vfio_mdev_ops,
>> +};
>> +
>> static const struct file_operations vd_fops = {
>> .owner = THIS_MODULE,
>> };
>> diff --git a/samples/vfio-mdev/mtty.c b/samples/vfio-mdev/mtty.c index
>> 744c88a6b22c..e427425b5daf 100644
>> --- a/samples/vfio-mdev/mtty.c
>> +++ b/samples/vfio-mdev/mtty.c
>> @@ -27,6 +27,7 @@
>> #include <linux/ctype.h>
>> #include <linux/file.h>
>> #include <linux/mdev.h>
>> +#include <linux/vfio_mdev.h>
>> #include <linux/pci.h>
>> #include <linux/serial.h>
>> #include <uapi/linux/serial_reg.h>
>> @@ -1410,6 +1411,14 @@ static struct attribute_group *mdev_type_groups[]
>> = {
>> NULL,
>> };
>>
>> +static const struct vfio_mdev_parent_ops vfio_mdev_ops = {
>> + .open = mtty_open,
>> + .release = mtty_close,
>> + .read = mtty_read,
>> + .write = mtty_write,
>> + .ioctl = mtty_ioctl,
>> +};
>> +
>> static const struct mdev_parent_ops mdev_fops = {
>> .owner = THIS_MODULE,
>> .dev_attr_groups = mtty_dev_groups,
>> @@ -1417,11 +1426,7 @@ static const struct mdev_parent_ops mdev_fops = {
>> .supported_type_groups = mdev_type_groups,
>> .create = mtty_create,
>> .remove = mtty_remove,
>> - .open = mtty_open,
>> - .release = mtty_close,
>> - .read = mtty_read,
>> - .write = mtty_write,
>> - .ioctl = mtty_ioctl,
>> + .device_ops = &vfio_mdev_ops,
>> };
>>
>> static void mtty_device_release(struct device *dev)
>> --
>> 2.19.1