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![Keith Packard](/assets/img/avatar_default.png)
Don't let a lessee control what the current DRM master is set to;
that's the job of the "real" master. Otherwise, the lessee would
disable all access to master operations for the owner and all lessees
under it.
This matches the same check made in the SET_MASTER ioctl.
Signed-off-by: Keith Packard <keithp@keithp.com>
Fixes: 2ed077e467
("drm: Add drm_object lease infrastructure [v5]")
Cc: <stable@vger.kernel.org> # v4.15+
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180119015159.1606-1-keithp@keithp.com
368 lines
9.8 KiB
C
368 lines
9.8 KiB
C
/*
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* Created: Tue Feb 2 08:37:54 1999 by faith@valinux.com
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*
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* Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
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* Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
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* All Rights Reserved.
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*
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* Author Rickard E. (Rik) Faith <faith@valinux.com>
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* Author Gareth Hughes <gareth@valinux.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <drm/drmP.h>
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#include "drm_internal.h"
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#include "drm_legacy.h"
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#include <drm/drm_lease.h>
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/**
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* DOC: master and authentication
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*
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* &struct drm_master is used to track groups of clients with open
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* primary/legacy device nodes. For every &struct drm_file which has had at
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* least once successfully became the device master (either through the
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* SET_MASTER IOCTL, or implicitly through opening the primary device node when
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* no one else is the current master that time) there exists one &drm_master.
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* This is noted in &drm_file.is_master. All other clients have just a pointer
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* to the &drm_master they are associated with.
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*
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* In addition only one &drm_master can be the current master for a &drm_device.
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* It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or
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* implicitly through closing/openeing the primary device node. See also
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* drm_is_current_master().
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*
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* Clients can authenticate against the current master (if it matches their own)
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* using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters,
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* this allows controlled access to the device for an entire group of mutually
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* trusted clients.
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*/
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int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
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{
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struct drm_auth *auth = data;
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int ret = 0;
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mutex_lock(&dev->master_mutex);
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if (!file_priv->magic) {
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ret = idr_alloc(&file_priv->master->magic_map, file_priv,
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1, 0, GFP_KERNEL);
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if (ret >= 0)
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file_priv->magic = ret;
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}
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auth->magic = file_priv->magic;
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mutex_unlock(&dev->master_mutex);
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DRM_DEBUG("%u\n", auth->magic);
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return ret < 0 ? ret : 0;
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}
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int drm_authmagic(struct drm_device *dev, void *data,
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struct drm_file *file_priv)
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{
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struct drm_auth *auth = data;
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struct drm_file *file;
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DRM_DEBUG("%u\n", auth->magic);
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mutex_lock(&dev->master_mutex);
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file = idr_find(&file_priv->master->magic_map, auth->magic);
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if (file) {
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file->authenticated = 1;
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idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
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}
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mutex_unlock(&dev->master_mutex);
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return file ? 0 : -EINVAL;
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}
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struct drm_master *drm_master_create(struct drm_device *dev)
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{
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struct drm_master *master;
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master = kzalloc(sizeof(*master), GFP_KERNEL);
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if (!master)
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return NULL;
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kref_init(&master->refcount);
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spin_lock_init(&master->lock.spinlock);
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init_waitqueue_head(&master->lock.lock_queue);
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idr_init(&master->magic_map);
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master->dev = dev;
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/* initialize the tree of output resource lessees */
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master->lessor = NULL;
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master->lessee_id = 0;
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INIT_LIST_HEAD(&master->lessees);
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INIT_LIST_HEAD(&master->lessee_list);
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idr_init(&master->leases);
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idr_init(&master->lessee_idr);
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return master;
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}
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static int drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
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bool new_master)
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{
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int ret = 0;
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dev->master = drm_master_get(fpriv->master);
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if (dev->driver->master_set) {
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ret = dev->driver->master_set(dev, fpriv, new_master);
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if (unlikely(ret != 0)) {
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drm_master_put(&dev->master);
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}
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}
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return ret;
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}
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static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
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{
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struct drm_master *old_master;
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int ret;
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lockdep_assert_held_once(&dev->master_mutex);
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old_master = fpriv->master;
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fpriv->master = drm_master_create(dev);
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if (!fpriv->master) {
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fpriv->master = old_master;
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return -ENOMEM;
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}
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if (dev->driver->master_create) {
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ret = dev->driver->master_create(dev, fpriv->master);
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if (ret)
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goto out_err;
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}
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fpriv->is_master = 1;
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fpriv->authenticated = 1;
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ret = drm_set_master(dev, fpriv, true);
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if (ret)
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goto out_err;
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if (old_master)
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drm_master_put(&old_master);
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return 0;
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out_err:
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/* drop references and restore old master on failure */
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drm_master_put(&fpriv->master);
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fpriv->master = old_master;
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return ret;
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}
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int drm_setmaster_ioctl(struct drm_device *dev, void *data,
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struct drm_file *file_priv)
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{
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int ret = 0;
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mutex_lock(&dev->master_mutex);
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if (drm_is_current_master(file_priv))
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goto out_unlock;
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if (dev->master) {
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ret = -EINVAL;
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goto out_unlock;
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}
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if (!file_priv->master) {
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ret = -EINVAL;
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goto out_unlock;
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}
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if (!file_priv->is_master) {
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ret = drm_new_set_master(dev, file_priv);
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goto out_unlock;
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}
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if (file_priv->master->lessor != NULL) {
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DRM_DEBUG_LEASE("Attempt to set lessee %d as master\n", file_priv->master->lessee_id);
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ret = -EINVAL;
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goto out_unlock;
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}
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ret = drm_set_master(dev, file_priv, false);
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out_unlock:
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mutex_unlock(&dev->master_mutex);
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return ret;
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}
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static void drm_drop_master(struct drm_device *dev,
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struct drm_file *fpriv)
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{
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if (dev->driver->master_drop)
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dev->driver->master_drop(dev, fpriv);
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drm_master_put(&dev->master);
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}
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int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
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struct drm_file *file_priv)
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{
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int ret = -EINVAL;
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mutex_lock(&dev->master_mutex);
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if (!drm_is_current_master(file_priv))
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goto out_unlock;
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if (!dev->master)
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goto out_unlock;
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if (file_priv->master->lessor != NULL) {
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DRM_DEBUG_LEASE("Attempt to drop lessee %d as master\n", file_priv->master->lessee_id);
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ret = -EINVAL;
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goto out_unlock;
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}
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ret = 0;
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drm_drop_master(dev, file_priv);
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out_unlock:
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mutex_unlock(&dev->master_mutex);
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return ret;
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}
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int drm_master_open(struct drm_file *file_priv)
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{
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struct drm_device *dev = file_priv->minor->dev;
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int ret = 0;
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/* if there is no current master make this fd it, but do not create
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* any master object for render clients */
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mutex_lock(&dev->master_mutex);
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if (!dev->master)
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ret = drm_new_set_master(dev, file_priv);
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else
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file_priv->master = drm_master_get(dev->master);
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mutex_unlock(&dev->master_mutex);
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return ret;
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}
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void drm_master_release(struct drm_file *file_priv)
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{
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struct drm_device *dev = file_priv->minor->dev;
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struct drm_master *master = file_priv->master;
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mutex_lock(&dev->master_mutex);
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if (file_priv->magic)
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idr_remove(&file_priv->master->magic_map, file_priv->magic);
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if (!drm_is_current_master(file_priv))
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goto out;
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if (drm_core_check_feature(dev, DRIVER_LEGACY)) {
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/*
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* Since the master is disappearing, so is the
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* possibility to lock.
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*/
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mutex_lock(&dev->struct_mutex);
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if (master->lock.hw_lock) {
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if (dev->sigdata.lock == master->lock.hw_lock)
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dev->sigdata.lock = NULL;
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master->lock.hw_lock = NULL;
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master->lock.file_priv = NULL;
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wake_up_interruptible_all(&master->lock.lock_queue);
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}
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mutex_unlock(&dev->struct_mutex);
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}
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if (dev->master == file_priv->master)
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drm_drop_master(dev, file_priv);
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out:
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if (drm_core_check_feature(dev, DRIVER_MODESET) && file_priv->is_master) {
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/* Revoke any leases held by this or lessees, but only if
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* this is the "real" master
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*/
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drm_lease_revoke(master);
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}
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/* drop the master reference held by the file priv */
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if (file_priv->master)
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drm_master_put(&file_priv->master);
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mutex_unlock(&dev->master_mutex);
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}
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/**
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* drm_is_current_master - checks whether @priv is the current master
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* @fpriv: DRM file private
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*
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* Checks whether @fpriv is current master on its device. This decides whether a
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* client is allowed to run DRM_MASTER IOCTLs.
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*
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* Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
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* - the current master is assumed to own the non-shareable display hardware.
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*/
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bool drm_is_current_master(struct drm_file *fpriv)
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{
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return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master;
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}
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EXPORT_SYMBOL(drm_is_current_master);
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/**
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* drm_master_get - reference a master pointer
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* @master: &struct drm_master
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*
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* Increments the reference count of @master and returns a pointer to @master.
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*/
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struct drm_master *drm_master_get(struct drm_master *master)
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{
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kref_get(&master->refcount);
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return master;
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}
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EXPORT_SYMBOL(drm_master_get);
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static void drm_master_destroy(struct kref *kref)
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{
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struct drm_master *master = container_of(kref, struct drm_master, refcount);
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struct drm_device *dev = master->dev;
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if (drm_core_check_feature(dev, DRIVER_MODESET))
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drm_lease_destroy(master);
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if (dev->driver->master_destroy)
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dev->driver->master_destroy(dev, master);
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drm_legacy_master_rmmaps(dev, master);
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idr_destroy(&master->magic_map);
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idr_destroy(&master->leases);
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idr_destroy(&master->lessee_idr);
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kfree(master->unique);
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kfree(master);
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}
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/**
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* drm_master_put - unreference and clear a master pointer
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* @master: pointer to a pointer of &struct drm_master
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*
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* This decrements the &drm_master behind @master and sets it to NULL.
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*/
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void drm_master_put(struct drm_master **master)
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{
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kref_put(&(*master)->refcount, drm_master_destroy);
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*master = NULL;
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}
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EXPORT_SYMBOL(drm_master_put);
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