linux/include/drm/drm_auth.h
Desmond Cheong Zhi Xi d793b8f732 drm: clarify usage of drm leases
We make the following changes to the documentation of drm leases to
make it easier to reason about their usage. In particular, we clarify
the lifetime and locking rules of lease fields in drm_master:

1. Make it clear that &drm_device.mode_config.idr_mutex protects the
lease idr and list structures for drm_master. The lessor field itself
doesn't need to be protected as it doesn't change after it's set in
drm_lease_create.

2. Add descriptions for the lifetime of lessors and leases.

3. Add an overview DOC: section in drm-uapi.rst that defines the
terminology for drm leasing, and explains how leases work and why
they're used.

Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210728102739.441543-1-desmondcheongzx@gmail.com
2021-07-29 09:12:01 +02:00

162 lines
4.6 KiB
C

#ifndef _DRM_AUTH_H_
#define _DRM_AUTH_H_
/*
* Internal Header for the Direct Rendering Manager
*
* Copyright 2016 Intel Corporation
*
* Author: Daniel Vetter <daniel.vetter@ffwll.ch>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include <linux/idr.h>
#include <linux/kref.h>
#include <linux/wait.h>
struct drm_file;
struct drm_hw_lock;
/*
* Legacy DRI1 locking data structure. Only here instead of in drm_legacy.h for
* include ordering reasons.
*
* DO NOT USE.
*/
struct drm_lock_data {
struct drm_hw_lock *hw_lock;
struct drm_file *file_priv;
wait_queue_head_t lock_queue;
unsigned long lock_time;
spinlock_t spinlock;
uint32_t kernel_waiters;
uint32_t user_waiters;
int idle_has_lock;
};
/**
* struct drm_master - drm master structure
*
* @refcount: Refcount for this master object.
* @dev: Link back to the DRM device
* @driver_priv: Pointer to driver-private information.
*
* Note that master structures are only relevant for the legacy/primary device
* nodes, hence there can only be one per device, not one per drm_minor.
*/
struct drm_master {
struct kref refcount;
struct drm_device *dev;
/**
* @unique: Unique identifier: e.g. busid. Protected by
* &drm_device.master_mutex.
*/
char *unique;
/**
* @unique_len: Length of unique field. Protected by
* &drm_device.master_mutex.
*/
int unique_len;
/**
* @magic_map: Map of used authentication tokens. Protected by
* &drm_device.master_mutex.
*/
struct idr magic_map;
void *driver_priv;
/**
* @lessor:
*
* Lease grantor, only set if this &struct drm_master represents a
* lessee holding a lease of objects from @lessor. Full owners of the
* device have this set to NULL.
*
* The lessor does not change once it's set in drm_lease_create(), and
* each lessee holds a reference to its lessor that it releases upon
* being destroyed in drm_lease_destroy().
*
* See also the :ref:`section on display resource leasing
* <drm_leasing>`.
*/
struct drm_master *lessor;
/**
* @lessee_id:
*
* ID for lessees. Owners (i.e. @lessor is NULL) always have ID 0.
* Protected by &drm_device.mode_config's &drm_mode_config.idr_mutex.
*/
int lessee_id;
/**
* @lessee_list:
*
* List entry of lessees of @lessor, where they are linked to @lessees.
* Not used for owners. Protected by &drm_device.mode_config's
* &drm_mode_config.idr_mutex.
*/
struct list_head lessee_list;
/**
* @lessees:
*
* List of drm_masters leasing from this one. Protected by
* &drm_device.mode_config's &drm_mode_config.idr_mutex.
*
* This list is empty if no leases have been granted, or if all lessees
* have been destroyed. Since lessors are referenced by all their
* lessees, this master cannot be destroyed unless the list is empty.
*/
struct list_head lessees;
/**
* @leases:
*
* Objects leased to this drm_master. Protected by
* &drm_device.mode_config's &drm_mode_config.idr_mutex.
*
* Objects are leased all together in drm_lease_create(), and are
* removed all together when the lease is revoked.
*/
struct idr leases;
/**
* @lessee_idr:
*
* All lessees under this owner (only used where @lessor is NULL).
* Protected by &drm_device.mode_config's &drm_mode_config.idr_mutex.
*/
struct idr lessee_idr;
/* private: */
#if IS_ENABLED(CONFIG_DRM_LEGACY)
struct drm_lock_data lock;
#endif
};
struct drm_master *drm_master_get(struct drm_master *master);
struct drm_master *drm_file_get_master(struct drm_file *file_priv);
void drm_master_put(struct drm_master **master);
bool drm_is_current_master(struct drm_file *fpriv);
struct drm_master *drm_master_create(struct drm_device *dev);
#endif