// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright © 2017 Keith Packard <[email protected]> */ #include <linux/file.h> #include <linux/uaccess.h> #include <drm/drm_auth.h> #include <drm/drm_crtc.h> #include <drm/drm_drv.h> #include <drm/drm_file.h> #include <drm/drm_lease.h> #include <drm/drm_print.h> #include "drm_crtc_internal.h" #include "drm_internal.h" /** * DOC: drm leasing * * DRM leases provide information about whether a DRM master may control a DRM * mode setting object. This enables the creation of multiple DRM masters that * manage subsets of display resources. * * The original DRM master of a device 'owns' the available drm resources. It * may create additional DRM masters and 'lease' resources which it controls * to the new DRM master. This gives the new DRM master control over the * leased resources until the owner revokes the lease, or the new DRM master * is closed. Some helpful terminology: * * - An 'owner' is a &struct drm_master that is not leasing objects from * another &struct drm_master, and hence 'owns' the objects. The owner can be * identified as the &struct drm_master for which &drm_master.lessor is NULL. * * - A 'lessor' is a &struct drm_master which is leasing objects to one or more * other &struct drm_master. Currently, lessees are not allowed to * create sub-leases, hence the lessor is the same as the owner. * * - A 'lessee' is a &struct drm_master which is leasing objects from some * other &struct drm_master. Each lessee only leases resources from a single * lessor recorded in &drm_master.lessor, and holds the set of objects that * it is leasing in &drm_master.leases. * * - A 'lease' is a contract between the lessor and lessee that identifies * which resources may be controlled by the lessee. All of the resources * that are leased must be owned by or leased to the lessor, and lessors are * not permitted to lease the same object to multiple lessees. * * The set of objects any &struct drm_master 'controls' is limited to the set * of objects it leases (for lessees) or all objects (for owners). * * Objects not controlled by a &struct drm_master cannot be modified through * the various state manipulating ioctls, and any state reported back to user * space will be edited to make them appear idle and/or unusable. For * instance, connectors always report 'disconnected', while encoders * report no possible crtcs or clones. * * Since each lessee may lease objects from a single lessor, display resource * leases form a tree of &struct drm_master. As lessees are currently not * allowed to create sub-leases, the tree depth is limited to 1. All of * these get activated simultaneously when the top level device owner changes * through the SETMASTER or DROPMASTER IOCTL, so &drm_device.master points to * the owner at the top of the lease tree (i.e. the &struct drm_master for which * &drm_master.lessor is NULL). The full list of lessees that are leasing * objects from the owner can be searched via the owner's * &drm_master.lessee_idr. */ #define drm_for_each_lessee(lessee, lessor) … static uint64_t drm_lease_idr_object; struct drm_master *drm_lease_owner(struct drm_master *master) { … } static struct drm_master* _drm_find_lessee(struct drm_master *master, int lessee_id) { … } static int _drm_lease_held_master(struct drm_master *master, int id) { … } /* Checks if the given object has been leased to some lessee of drm_master */ static bool _drm_has_leased(struct drm_master *master, int id) { … } /* Called with idr_mutex held */ bool _drm_lease_held(struct drm_file *file_priv, int id) { … } bool drm_lease_held(struct drm_file *file_priv, int id) { … } /* * Given a bitmask of crtcs to check, reconstructs a crtc mask based on the * crtcs which are visible through the specified file. */ uint32_t drm_lease_filter_crtcs(struct drm_file *file_priv, uint32_t crtcs_in) { … } /* * Uses drm_master_create to allocate a new drm_master, then checks to * make sure all of the desired objects can be leased, atomically * leasing them to the new drmmaster. * * ERR_PTR(-EACCES) some other master holds the title to any object * ERR_PTR(-ENOENT) some object is not a valid DRM object for this device * ERR_PTR(-EBUSY) some other lessee holds title to this object * ERR_PTR(-EEXIST) same object specified more than once in the provided list * ERR_PTR(-ENOMEM) allocation failed */ static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr *leases) { … } void drm_lease_destroy(struct drm_master *master) { … } static void _drm_lease_revoke(struct drm_master *top) { … } void drm_lease_revoke(struct drm_master *top) { … } static int validate_lease(struct drm_device *dev, int object_count, struct drm_mode_object **objects, bool universal_planes) { … } static int fill_object_idr(struct drm_device *dev, struct drm_file *lessor_priv, struct idr *leases, int object_count, u32 *object_ids) { … } /* * The master associated with the specified file will have a lease * created containing the objects specified in the ioctl structure. * A file descriptor will be allocated for that and returned to the * application. */ int drm_mode_create_lease_ioctl(struct drm_device *dev, void *data, struct drm_file *lessor_priv) { … } int drm_mode_list_lessees_ioctl(struct drm_device *dev, void *data, struct drm_file *lessor_priv) { … } /* Return the list of leased objects for the specified lessee */ int drm_mode_get_lease_ioctl(struct drm_device *dev, void *data, struct drm_file *lessee_priv) { … } /* * This removes all of the objects from the lease without * actually getting rid of the lease itself; that way all * references to it still work correctly */ int drm_mode_revoke_lease_ioctl(struct drm_device *dev, void *data, struct drm_file *lessor_priv) { … }
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