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    SubjectRe: [RFC v1 7/8] mshv: implement in-kernel device framework
    On Wed, Aug 04, 2021 at 12:42:22AM +0530, Praveen Kumar wrote:
    > On 09-07-2021 17:13, Wei Liu wrote:
    [...]
    > > +static long mshv_device_ioctl(struct file *filp, unsigned int ioctl,
    > > + unsigned long arg)
    > > +{
    > > + struct mshv_device *dev = filp->private_data;
    > > +
    > > + switch (ioctl) {
    > > + case MSHV_SET_DEVICE_ATTR:
    > > + return mshv_device_ioctl_attr(dev, dev->ops->set_attr, arg);
    > > + case MSHV_GET_DEVICE_ATTR:
    > > + return mshv_device_ioctl_attr(dev, dev->ops->get_attr, arg);
    > > + case MSHV_HAS_DEVICE_ATTR:
    > > + return mshv_device_ioctl_attr(dev, dev->ops->has_attr, arg);
    > > + default:
    > > + if (dev->ops->ioctl)
    > > + return dev->ops->ioctl(dev, ioctl, arg);
    > > +
    > > + return -ENOTTY;
    > > + }
    >
    > Have seen some static analyzer tool cribbing here of not returning any error.
    > If you feel OK, please move the 'return -ENOTTY' down after switch block. Thanks.
    >

    Fair point. I will make the change.

    > > +}
    > > +
    [...]
    > > +static long
    > > +mshv_partition_ioctl_create_device(struct mshv_partition *partition,
    > > + void __user *user_args)
    > > +{
    > > + long r;
    > > + struct mshv_create_device tmp, *cd;
    > > + struct mshv_device *dev;
    > > + const struct mshv_device_ops *ops;
    > > + int type;
    > > +
    > > + if (copy_from_user(&tmp, user_args, sizeof(tmp))) {
    > > + r = -EFAULT;
    > > + goto out;
    > > + }
    > > +
    > > + cd = &tmp;
    > > +
    > > + if (cd->type >= ARRAY_SIZE(mshv_device_ops_table)) {
    > > + r = -ENODEV;
    > > + goto out;
    > > + }
    > > +
    > > + type = array_index_nospec(cd->type, ARRAY_SIZE(mshv_device_ops_table));
    > > + ops = mshv_device_ops_table[type];
    > > + if (ops == NULL) {
    > > + r = -ENODEV;
    > > + goto out;
    > > + }
    > > +
    > > + if (cd->flags & MSHV_CREATE_DEVICE_TEST) {
    > > + r = 0;
    > > + goto out;
    > > + }
    > > +
    > > + dev = kzalloc(sizeof(*dev), GFP_KERNEL_ACCOUNT);
    > > + if (!dev) {
    > > + r = -ENOMEM;
    > > + goto out;
    > > + }
    > > +
    > > + dev->ops = ops;
    > > + dev->partition = partition;
    > > +
    > > + r = ops->create(dev, type);
    > > + if (r < 0) {
    > > + kfree(dev);
    > > + goto out;
    > > + }
    > > +
    > > + list_add(&dev->partition_node, &partition->devices);
    > > +
    > > + if (ops->init)
    > > + ops->init(dev);
    > > +
    > > + mshv_partition_get(partition);
    > > + r = anon_inode_getfd(ops->name, &mshv_device_fops, dev, O_RDWR | O_CLOEXEC);
    > > + if (r < 0) {
    > > + mshv_partition_put_no_destroy(partition);
    > > + list_del(&dev->partition_node);
    > > + ops->destroy(dev);
    >
    > I hope ops->destroy will free dev as well ?

    Yes. It is clearly written in the preceding comment of that hook. I hope
    that's prominent enough.

    >
    > > + goto out;
    > > + }
    > > +
    > > + cd->fd = r;
    > > + r = 0;
    > > +
    > > + if (copy_to_user(user_args, &tmp, sizeof(tmp))) {
    > > + r = -EFAULT;
    >
    > I don't think we will be cleaning up anything ? Or do we need to?

    No need. Whatever residuals left will be cleaned up once the VM is
    destroyed.

    Wei.

    > > + goto out;
    > > + }
    > > +out:
    > > + return r;
    > > +}
    > > +
    >
    > Regards,
    >
    > ~Praveen.

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