1 files changed, 355 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c
new file mode 100644
index 000000000000..030db1170570
--- /dev/null
+++ b/drivers/gpu/drm/drm_lease.c
@@ -0,0 +1,355 @@
+/*
+ * Copyright © 2017 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <drm/drmP.h>
+#include "drm_internal.h"
+#include "drm_legacy.h"
+#include "drm_crtc_internal.h"
+#include <drm/drm_lease.h>
+#include <drm/drm_auth.h>
+#include <drm/drm_crtc_helper.h>
+
+#define drm_for_each_lessee(lessee, lessor) \
+	list_for_each_entry((lessee), &(lessor)->lessees, lessee_list)
+
+/**
+ * drm_lease_owner - return ancestor owner drm_master
+ * @master: drm_master somewhere within tree of lessees and lessors
+ *
+ * RETURN:
+ *
+ * drm_master at the top of the tree (i.e, with lessor NULL
+ */
+struct drm_master *drm_lease_owner(struct drm_master *master)
+{
+	while (master->lessor != NULL)
+		master = master->lessor;
+	return master;
+}
+EXPORT_SYMBOL(drm_lease_owner);
+
+/**
+ * _drm_find_lessee - find lessee by id (idr_mutex held)
+ * @master: drm_master of lessor
+ * @id: lessee_id
+ *
+ * RETURN:
+ *
+ * drm_master of the lessee if valid, NULL otherwise
+ */
+
+static struct drm_master*
+_drm_find_lessee(struct drm_master *master, int lessee_id)
+{
+	lockdep_assert_held(&master->dev->mode_config.idr_mutex);
+	return idr_find(&drm_lease_owner(master)->lessee_idr, lessee_id);
+}
+
+/**
+ * _drm_lease_held_master - check to see if an object is leased (or owned) by master (idr_mutex held)
+ * @master: the master to check the lease status of
+ * @id: the id to check
+ *
+ * Checks if the specified master holds a lease on the object. Return
+ * value:
+ *
+ *	true		'master' holds a lease on (or owns) the object
+ *	false		'master' does not hold a lease.
+ */
+static int _drm_lease_held_master(struct drm_master *master, int id)
+{
+	lockdep_assert_held(&master->dev->mode_config.idr_mutex);
+	if (master->lessor)
+		return idr_find(&master->leases, id) != NULL;
+	return true;
+}
+
+/**
+ * _drm_has_leased - check to see if an object has been leased (idr_mutex held)
+ * @master: the master to check the lease status of
+ * @id: the id to check
+ *
+ * Checks if any lessee of 'master' holds a lease on 'id'. Return
+ * value:
+ *
+ *	true		Some lessee holds a lease on the object.
+ *	false		No lessee has a lease on the object.
+ */
+static bool _drm_has_leased(struct drm_master *master, int id)
+{
+	struct drm_master *lessee;
+
+	lockdep_assert_held(&master->dev->mode_config.idr_mutex);
+	drm_for_each_lessee(lessee, master)
+		if (_drm_lease_held_master(lessee, id))
+			return true;
+	return false;
+}
+
+/**
+ * _drm_lease_held - check drm_mode_object lease status (idr_mutex held)
+ * @master: the drm_master
+ * @id: the object id
+ *
+ * Checks if the specified master holds a lease on the object. Return
+ * value:
+ *
+ *	true		'master' holds a lease on (or owns) the object
+ *	false		'master' does not hold a lease.
+ */
+bool _drm_lease_held(struct drm_file *file_priv, int id)
+{
+	if (file_priv == NULL || file_priv->master == NULL)
+		return true;
+
+	return _drm_lease_held_master(file_priv->master, id);
+}
+EXPORT_SYMBOL(_drm_lease_held);
+
+/**
+ * drm_lease_held - check drm_mode_object lease status (idr_mutex not held)
+ * @master: the drm_master
+ * @id: the object id
+ *
+ * Checks if the specified master holds a lease on the object. Return
+ * value:
+ *
+ *	true		'master' holds a lease on (or owns) the object
+ *	false		'master' does not hold a lease.
+ */
+bool drm_lease_held(struct drm_file *file_priv, int id)
+{
+	struct drm_master *master;
+	bool ret;
+
+	if (file_priv == NULL || file_priv->master == NULL)
+		return true;
+
+	master = file_priv->master;
+	mutex_lock(&master->dev->mode_config.idr_mutex);
+	ret = _drm_lease_held_master(master, id);
+	mutex_unlock(&master->dev->mode_config.idr_mutex);
+	return ret;
+}
+EXPORT_SYMBOL(drm_lease_held);
+
+/**
+ * drm_lease_filter_crtcs - restricted crtc set to leased values (idr_mutex not held)
+ * @file_priv: requestor file
+ * @crtcs: 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)
+{
+	struct drm_master *master;
+	struct drm_device *dev;
+	struct drm_crtc *crtc;
+	int count_in, count_out;
+	uint32_t crtcs_out = 0;
+
+	if (file_priv == NULL || file_priv->master == NULL)
+		return crtcs_in;
+
+	master = file_priv->master;
+	dev = master->dev;
+
+	count_in = count_out = 0;
+	mutex_lock(&master->dev->mode_config.idr_mutex);
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+		if (_drm_lease_held_master(master, crtc->base.id)) {
+			uint32_t mask_in = 1ul << count_in;
+			if ((crtcs_in & mask_in) != 0) {
+				uint32_t mask_out = 1ul << count_out;
+				crtcs_out |= mask_out;
+			}
+			count_out++;
+		}
+		count_in++;
+	}
+	mutex_unlock(&master->dev->mode_config.idr_mutex);
+	return crtcs_out;
+}
+EXPORT_SYMBOL(drm_lease_filter_crtcs);
+
+/*
+ * drm_lease_create - create a new drm_master with leased objects (idr_mutex not held)
+ * @lessor: lease holder (or owner) of objects
+ * @leases: objects to lease to the new drm_master
+ *
+ * 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(-EACCESS)	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)
+{
+	struct drm_device *dev = lessor->dev;
+	int error;
+	struct drm_master *lessee;
+	int object;
+	int id;
+	void *entry;
+
+	DRM_DEBUG_LEASE("lessor %d\n", lessor->lessee_id);
+
+	lessee = drm_master_create(lessor->dev);
+	if (!lessee) {
+		DRM_DEBUG_LEASE("drm_master_create failed\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	mutex_lock(&dev->mode_config.idr_mutex);
+
+	/* Insert the new lessee into the tree */
+	id = idr_alloc(&(drm_lease_owner(lessor)->lessee_idr), lessee, 1, 0, GFP_KERNEL);
+	if (id < 0) {
+		error = id;
+		goto out_lessee;
+	}
+
+	lessee->lessee_id = id;
+	lessee->lessor = drm_master_get(lessor);
+	list_add_tail(&lessee->lessee_list, &lessor->lessees);
+
+	idr_for_each_entry(leases, entry, object) {
+		error = 0;
+		if (!idr_find(&dev->mode_config.crtc_idr, object))
+			error = -ENOENT;
+		else if (!_drm_lease_held_master(lessor, object))
+			error = -EACCES;
+		else if (_drm_has_leased(lessor, object))
+			error = -EBUSY;
+
+		if (error != 0) {
+			DRM_DEBUG_LEASE("object %d failed %d\n", object, error);
+			goto out_lessee;
+		}
+	}
+
+	/* Move the leases over */
+	lessee->leases = *leases;
+	DRM_DEBUG_LEASE("new lessee %d %p, lessor %d %p\n", lessee->lessee_id, lessee, lessor->lessee_id, lessor);
+
+	mutex_unlock(&dev->mode_config.idr_mutex);
+	return lessee;
+
+out_lessee:
+	drm_master_put(&lessee);
+
+	mutex_unlock(&dev->mode_config.idr_mutex);
+
+	return ERR_PTR(error);
+}
+
+/**
+ * drm_lease_destroy - a master is going away (idr_mutex not held)
+ * @master: the drm_master being destroyed
+ *
+ * All lessees will have been destroyed as they
+ * hold a reference on their lessor. Notify any
+ * lessor for this master so that it can check
+ * the list of lessees.
+ */
+void drm_lease_destroy(struct drm_master *master)
+{
+	struct drm_device *dev = master->dev;
+
+	mutex_lock(&dev->mode_config.idr_mutex);
+
+	DRM_DEBUG_LEASE("drm_lease_destroy %d\n", master->lessee_id);
+
+	/* This master is referenced by all lessees, hence it cannot be destroyed
+	 * until all of them have been
+	 */
+	WARN_ON(!list_empty(&master->lessees));
+
+	/* Remove this master from the lessee idr in the owner */
+	if (master->lessee_id != 0) {
+		DRM_DEBUG_LEASE("remove master %d from device list of lessees\n", master->lessee_id);
+		idr_remove(&(drm_lease_owner(master)->lessee_idr), master->lessee_id);
+	}
+
+	/* Remove this master from any lessee list it may be on */
+	list_del(&master->lessee_list);
+
+	mutex_unlock(&dev->mode_config.idr_mutex);
+
+	if (master->lessor) {
+		/* Tell the master to check the lessee list */
+		drm_sysfs_hotplug_event(dev);
+		drm_master_put(&master->lessor);
+	}
+
+	DRM_DEBUG_LEASE("drm_lease_destroy done %d\n", master->lessee_id);
+}
+
+/**
+ * _drm_lease_revoke - revoke access to all leased objects (idr_mutex held)
+ * @master: the master losing its lease
+ */
+static void _drm_lease_revoke(struct drm_master *top)
+{
+	int object;
+	void *entry;
+	struct drm_master *master = top;
+
+	lockdep_assert_held(&top->dev->mode_config.idr_mutex);
+
+	/*
+	 * Walk the tree starting at 'top' emptying all leases. Because
+	 * the tree is fully connected, we can do this without recursing
+	 */
+	for (;;) {
+		DRM_DEBUG_LEASE("revoke leases for %p %d\n", master, master->lessee_id);
+
+		/* Evacuate the lease */
+		idr_for_each_entry(&master->leases, entry, object)
+			idr_remove(&master->leases, object);
+
+		/* Depth-first list walk */
+
+		/* Down */
+		if (!list_empty(&master->lessees)) {
+			master = list_first_entry(&master->lessees, struct drm_master, lessee_list);
+		} else {
+			/* Up */
+			while (master != top && master == list_last_entry(&master->lessor->lessees, struct drm_master, lessee_list))
+				master = master->lessor;
+
+			if (master == top)
+				break;
+
+			/* Over */
+			master = list_entry(master->lessee_list.next, struct drm_master, lessee_list);
+		}
+	}
+}
+
+/**
+ * drm_lease_revoke - revoke access to all leased objects (idr_mutex not held)
+ * @top: the master losing its lease
+ */
+void drm_lease_revoke(struct drm_master *top)
+{
+	mutex_lock(&top->dev->mode_config.idr_mutex);
+	_drm_lease_revoke(top);
+	mutex_unlock(&top->dev->mode_config.idr_mutex);
+}