Yi Liu 330c179976 vfio: Move "device->open_count--" out of group_rwsem in vfio_device_open()
We do not protect the vfio_device::open_count with group_rwsem elsewhere (see
vfio_device_fops_release as a comparison, where we already drop group_rwsem
before open_count--). So move the group_rwsem unlock prior to open_count--.

This change now also drops group_rswem before setting device->kvm = NULL,
but that's also OK (again, just like vfio_device_fops_release). The setting
of device->kvm before open_device is technically done while holding the
group_rwsem, this is done to protect the group kvm value we are copying from,
and we should not be relying on that to protect the contents of device->kvm;
instead we assume this value will not change until after the device is closed
and while under the dev_set->lock.

Cc: Matthew Rosato <mjrosato@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20220627074119.523274-1-yi.l.liu@intel.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2022-06-30 11:07:07 -06:00
2022-06-26 14:22:10 -07:00

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.
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