9cef73918e
Modernize how vfio is creating the group char dev and sysfs presence. These days drivers with state should use cdev_device_add() and cdev_device_del() to manage the cdev and sysfs lifetime. This API requires the driver to put the struct device and struct cdev inside its state struct (vfio_group), and then use the usual device_initialize()/cdev_device_add()/cdev_device_del() sequence. Split the code to make this possible: - vfio_group_alloc()/vfio_group_release() are pair'd functions to alloc/free the vfio_group. release is done under the struct device kref. - vfio_create_group()/vfio_group_put() are pairs that manage the sysfs/cdev lifetime. Once the uses count is zero the vfio group's userspace presence is destroyed. - The IDR is replaced with an IDA. container_of(inode->i_cdev) is used to get back to the vfio_group during fops open. The IDA assigns unique minor numbers. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Link: https://lore.kernel.org/r/5-v3-2fdfe4ca2cc6+18c-vfio_group_cdev_jgg@nvidia.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.