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0e79a47fb1
Each file descriptor gets a chunk of per-FD driver specific context that allows the driver to attach a device specific struct to. The core code takes care of the memory lifetime for this structure. The ioctl dispatch and design is based on what was built for iommufd. The ioctls have a struct which has a combined in/out behavior with a typical 'zero pad' scheme for future extension and backwards compatibility. Like iommufd some shared logic does most of the ioctl marshaling and compatibility work and table dispatches to some function pointers for each unique ioctl. This approach has proven to work quite well in the iommufd and rdma subsystems. Allocate an ioctl number space for the subsystem. Link: https://patch.msgid.link/r/2-v5-642aa0c94070+4447f-fwctl_jgg@nvidia.com Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Reviewed-by: Dave Jiang <dave.jiang@intel.com> Reviewed-by: Shannon Nelson <shannon.nelson@amd.com> Tested-by: Dave Jiang <dave.jiang@intel.com> Tested-by: Shannon Nelson <shannon.nelson@amd.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>