/*
 * Copyright (c) 2016 Intel Corporation
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */

#include <linux/export.h>
#include <drm/drmP.h>
#include <drm/drm_property.h>

#include "drm_crtc_internal.h"

/**
 * DOC: overview
 *
 * Properties as represented by &drm_property are used to extend the modeset
 * interface exposed to userspace. For the atomic modeset IOCTL properties are
 * even the only way to transport metadata about the desired new modeset
 * configuration from userspace to the kernel. Properties have a well-defined
 * value range, which is enforced by the drm core. See the documentation of the
 * flags member of &struct drm_property for an overview of the different
 * property types and ranges.
 *
 * Properties don't store the current value directly, but need to be
 * instatiated by attaching them to a &drm_mode_object with
 * drm_object_attach_property().
 *
 * Property values are only 64bit. To support bigger piles of data (like gamma
 * tables, color correction matrices or large structures) a property can instead
 * point at a &drm_property_blob with that additional data.
 *
 * Properties are defined by their symbolic name, userspace must keep a
 * per-object mapping from those names to the property ID used in the atomic
 * IOCTL and in the get/set property IOCTL.
 */

static bool drm_property_flags_valid(u32 flags)
{
        u32 legacy_type = flags & DRM_MODE_PROP_LEGACY_TYPE;
        u32 ext_type = flags & DRM_MODE_PROP_EXTENDED_TYPE;

        /* Reject undefined/deprecated flags */
        if (flags & ~(DRM_MODE_PROP_LEGACY_TYPE |
                      DRM_MODE_PROP_EXTENDED_TYPE |
                      DRM_MODE_PROP_IMMUTABLE |
                      DRM_MODE_PROP_ATOMIC))
                return false;

        /* We want either a legacy type or an extended type, but not both */
        if (!legacy_type == !ext_type)
                return false;

        /* Only one legacy type at a time please */
        if (legacy_type && !is_power_of_2(legacy_type))
                return false;

        return true;
}

/**
 * drm_property_create - create a new property type
 * @dev: drm device
 * @flags: flags specifying the property type
 * @name: name of the property
 * @num_values: number of pre-defined values
 *
 * This creates a new generic drm property which can then be attached to a drm
 * object with drm_object_attach_property(). The returned property object must
 * be freed with drm_property_destroy(), which is done automatically when
 * calling drm_mode_config_cleanup().
 *
 * Returns:
 * A pointer to the newly created property on success, NULL on failure.
 */
struct drm_property *drm_property_create(struct drm_device *dev,
                                         u32 flags, const char *name,
                                         int num_values)
{
        struct drm_property *property = NULL;
        int ret;

        if (WARN_ON(!drm_property_flags_valid(flags)))
                return NULL;

        if (WARN_ON(strlen(name) >= DRM_PROP_NAME_LEN))
                return NULL;

        property = kzalloc(sizeof(struct drm_property), GFP_KERNEL);
        if (!property)
                return NULL;

        property->dev = dev;

        if (num_values) {
                property->values = kcalloc(num_values, sizeof(uint64_t),
                                           GFP_KERNEL);
                if (!property->values)
                        goto fail;
        }

        ret = drm_mode_object_add(dev, &property->base, DRM_MODE_OBJECT_PROPERTY);
        if (ret)
                goto fail;

        property->flags = flags;
        property->num_values = num_values;
        INIT_LIST_HEAD(&property->enum_list);

        strncpy(property->name, name, DRM_PROP_NAME_LEN);
        property->name[DRM_PROP_NAME_LEN-1] = '\0';

        list_add_tail(&property->head, &dev->mode_config.property_list);

        return property;
fail:
        kfree(property->values);
        kfree(property);
        return NULL;
}
EXPORT_SYMBOL(drm_property_create);

/**
 * drm_property_create_enum - create a new enumeration property type
 * @dev: drm device
 * @flags: flags specifying the property type
 * @name: name of the property
 * @props: enumeration lists with property values
 * @num_values: number of pre-defined values
 *
 * This creates a new generic drm property which can then be attached to a drm
 * object with drm_object_attach_property(). The returned property object must
 * be freed with drm_property_destroy(), which is done automatically when
 * calling drm_mode_config_cleanup().
 *
 * Userspace is only allowed to set one of the predefined values for enumeration
 * properties.
 *
 * Returns:
 * A pointer to the newly created property on success, NULL on failure.
 */
struct drm_property *drm_property_create_enum(struct drm_device *dev,
                                              u32 flags, const char *name,
                                              const struct drm_prop_enum_list *props,
                                              int num_values)
{
        struct drm_property *property;
        int i, ret;

        flags |= DRM_MODE_PROP_ENUM;

        property = drm_property_create(dev, flags, name, num_values);
        if (!property)
                return NULL;

        for (i = 0; i < num_values; i++) {
                ret = drm_property_add_enum(property,
                                            props[i].type,
                                            props[i].name);
                if (ret) {
                        drm_property_destroy(dev, property);
                        return NULL;
                }
        }

        return property;
}
EXPORT_SYMBOL(drm_property_create_enum);

/**
 * drm_property_create_bitmask - create a new bitmask property type
 * @dev: drm device
 * @flags: flags specifying the property type
 * @name: name of the property
 * @props: enumeration lists with property bitflags
 * @num_props: size of the @props array
 * @supported_bits: bitmask of all supported enumeration values
 *
 * This creates a new bitmask drm property which can then be attached to a drm
 * object with drm_object_attach_property(). The returned property object must
 * be freed with drm_property_destroy(), which is done automatically when
 * calling drm_mode_config_cleanup().
 *
 * Compared to plain enumeration properties userspace is allowed to set any
 * or'ed together combination of the predefined property bitflag values
 *
 * Returns:
 * A pointer to the newly created property on success, NULL on failure.
 */
struct drm_property *drm_property_create_bitmask(struct drm_device *dev,
                                                 u32 flags, const char *name,
                                                 const struct drm_prop_enum_list *props,
                                                 int num_props,
                                                 uint64_t supported_bits)
{
        struct drm_property *property;
        int i, ret;
        int num_values = hweight64(supported_bits);

        flags |= DRM_MODE_PROP_BITMASK;

        property = drm_property_create(dev, flags, name, num_values);
        if (!property)
                return NULL;
        for (i = 0; i < num_props; i++) {
                if (!(supported_bits & (1ULL << props[i].type)))
                        continue;

                ret = drm_property_add_enum(property,
                                            props[i].type,
                                            props[i].name);
                if (ret) {
                        drm_property_destroy(dev, property);
                        return NULL;
                }
        }

        return property;
}
EXPORT_SYMBOL(drm_property_create_bitmask);

static struct drm_property *property_create_range(struct drm_device *dev,
                                                  u32 flags, const char *name,
                                                  uint64_t min, uint64_t max)
{
        struct drm_property *property;

        property = drm_property_create(dev, flags, name, 2);
        if (!property)
                return NULL;

        property->values[0] = min;
        property->values[1] = max;

        return property;
}

/**
 * drm_property_create_range - create a new unsigned ranged property type
 * @dev: drm device
 * @flags: flags specifying the property type
 * @name: name of the property
 * @min: minimum value of the property
 * @max: maximum value of the property
 *
 * This creates a new generic drm property which can then be attached to a drm
 * object with drm_object_attach_property(). The returned property object must
 * be freed with drm_property_destroy(), which is done automatically when
 * calling drm_mode_config_cleanup().
 *
 * Userspace is allowed to set any unsigned integer value in the (min, max)
 * range inclusive.
 *
 * Returns:
 * A pointer to the newly created property on success, NULL on failure.
 */
struct drm_property *drm_property_create_range(struct drm_device *dev,
                                               u32 flags, const char *name,
                                               uint64_t min, uint64_t max)
{
        return property_create_range(dev, DRM_MODE_PROP_RANGE | flags,
                        name, min, max);
}
EXPORT_SYMBOL(drm_property_create_range);

/**
 * drm_property_create_signed_range - create a new signed ranged property type
 * @dev: drm device
 * @flags: flags specifying the property type
 * @name: name of the property
 * @min: minimum value of the property
 * @max: maximum value of the property
 *
 * This creates a new generic drm property which can then be attached to a drm
 * object with drm_object_attach_property(). The returned property object must
 * be freed with drm_property_destroy(), which is done automatically when
 * calling drm_mode_config_cleanup().
 *
 * Userspace is allowed to set any signed integer value in the (min, max)
 * range inclusive.
 *
 * Returns:
 * A pointer to the newly created property on success, NULL on failure.
 */
struct drm_property *drm_property_create_signed_range(struct drm_device *dev,
                                                      u32 flags, const char *name,
                                                      int64_t min, int64_t max)
{
        return property_create_range(dev, DRM_MODE_PROP_SIGNED_RANGE | flags,
                        name, I642U64(min), I642U64(max));
}
EXPORT_SYMBOL(drm_property_create_signed_range);

/**
 * drm_property_create_object - create a new object property type
 * @dev: drm device
 * @flags: flags specifying the property type
 * @name: name of the property
 * @type: object type from DRM_MODE_OBJECT_* defines
 *
 * This creates a new generic drm property which can then be attached to a drm
 * object with drm_object_attach_property(). The returned property object must
 * be freed with drm_property_destroy(), which is done automatically when
 * calling drm_mode_config_cleanup().
 *
 * Userspace is only allowed to set this to any property value of the given
 * @type. Only useful for atomic properties, which is enforced.
 *
 * Returns:
 * A pointer to the newly created property on success, NULL on failure.
 */
struct drm_property *drm_property_create_object(struct drm_device *dev,
                                                u32 flags, const char *name,
                                                uint32_t type)
{
        struct drm_property *property;

        flags |= DRM_MODE_PROP_OBJECT;

        if (WARN_ON(!(flags & DRM_MODE_PROP_ATOMIC)))
                return NULL;

        property = drm_property_create(dev, flags, name, 1);
        if (!property)
                return NULL;

        property->values[0] = type;

        return property;
}
EXPORT_SYMBOL(drm_property_create_object);

/**
 * drm_property_create_bool - create a new boolean property type
 * @dev: drm device
 * @flags: flags specifying the property type
 * @name: name of the property
 *
 * This creates a new generic drm property which can then be attached to a drm
 * object with drm_object_attach_property(). The returned property object must
 * be freed with drm_property_destroy(), which is done automatically when
 * calling drm_mode_config_cleanup().
 *
 * This is implemented as a ranged property with only {0, 1} as valid values.
 *
 * Returns:
 * A pointer to the newly created property on success, NULL on failure.
 */
struct drm_property *drm_property_create_bool(struct drm_device *dev,
                                              u32 flags, const char *name)
{
        return drm_property_create_range(dev, flags, name, 0, 1);
}
EXPORT_SYMBOL(drm_property_create_bool);

/**
 * drm_property_add_enum - add a possible value to an enumeration property
 * @property: enumeration property to change
 * @value: value of the new enumeration
 * @name: symbolic name of the new enumeration
 *
 * This functions adds enumerations to a property.
 *
 * It's use is deprecated, drivers should use one of the more specific helpers
 * to directly create the property with all enumerations already attached.
 *
 * Returns:
 * Zero on success, error code on failure.
 */
int drm_property_add_enum(struct drm_property *property,
                          uint64_t value, const char *name)
{
        struct drm_property_enum *prop_enum;
        int index = 0;

        if (WARN_ON(strlen(name) >= DRM_PROP_NAME_LEN))
                return -EINVAL;

        if (WARN_ON(!drm_property_type_is(property, DRM_MODE_PROP_ENUM) &&
                    !drm_property_type_is(property, DRM_MODE_PROP_BITMASK)))
                return -EINVAL;

        /*
         * Bitmask enum properties have the additional constraint of values
         * from 0 to 63
         */
        if (WARN_ON(drm_property_type_is(property, DRM_MODE_PROP_BITMASK) &&
                    value > 63))
                return -EINVAL;

        list_for_each_entry(prop_enum, &property->enum_list, head) {
                if (WARN_ON(prop_enum->value == value))
                        return -EINVAL;
                index++;
        }

        if (WARN_ON(index >= property->num_values))
                return -EINVAL;

        prop_enum = kzalloc(sizeof(struct drm_property_enum), GFP_KERNEL);
        if (!prop_enum)
                return -ENOMEM;

        strncpy(prop_enum->name, name, DRM_PROP_NAME_LEN);
        prop_enum->name[DRM_PROP_NAME_LEN-1] = '\0';
        prop_enum->value = value;

        property->values[index] = value;
        list_add_tail(&prop_enum->head, &property->enum_list);
        return 0;
}
EXPORT_SYMBOL(drm_property_add_enum);

/**
 * drm_property_destroy - destroy a drm property
 * @dev: drm device
 * @property: property to destry
 *
 * This function frees a property including any attached resources like
 * enumeration values.
 */
void drm_property_destroy(struct drm_device *dev, struct drm_property *property)
{
        struct drm_property_enum *prop_enum, *pt;

        list_for_each_entry_safe(prop_enum, pt, &property->enum_list, head) {
                list_del(&prop_enum->head);
                kfree(prop_enum);
        }

        if (property->num_values)
                kfree(property->values);
        drm_mode_object_unregister(dev, &property->base);
        list_del(&property->head);
        kfree(property);
}
EXPORT_SYMBOL(drm_property_destroy);

int drm_mode_getproperty_ioctl(struct drm_device *dev,
                               void *data, struct drm_file *file_priv)
{
        struct drm_mode_get_property *out_resp = data;
        struct drm_property *property;
        int enum_count = 0;
        int value_count = 0;
        int i, copied;
        struct drm_property_enum *prop_enum;
        struct drm_mode_property_enum __user *enum_ptr;
        uint64_t __user *values_ptr;

        if (!drm_core_check_feature(dev, DRIVER_MODESET))
                return -EOPNOTSUPP;

        property = drm_property_find(dev, file_priv, out_resp->prop_id);
        if (!property)
                return -ENOENT;

        strncpy(out_resp->name, property->name, DRM_PROP_NAME_LEN);
        out_resp->name[DRM_PROP_NAME_LEN-1] = 0;
        out_resp->flags = property->flags;

        value_count = property->num_values;
        values_ptr = u64_to_user_ptr(out_resp->values_ptr);

        for (i = 0; i < value_count; i++) {
                if (i < out_resp->count_values &&
                    put_user(property->values[i], values_ptr + i)) {
                        return -EFAULT;
                }
        }
        out_resp->count_values = value_count;

        copied = 0;
        enum_ptr = u64_to_user_ptr(out_resp->enum_blob_ptr);

        if (drm_property_type_is(property, DRM_MODE_PROP_ENUM) ||
            drm_property_type_is(property, DRM_MODE_PROP_BITMASK)) {
                list_for_each_entry(prop_enum, &property->enum_list, head) {
                        enum_count++;
                        if (out_resp->count_enum_blobs < enum_count)
                                continue;

                        if (copy_to_user(&enum_ptr[copied].value,
                                         &prop_enum->value, sizeof(uint64_t)))
                                return -EFAULT;

                        if (copy_to_user(&enum_ptr[copied].name,
                                         &prop_enum->name, DRM_PROP_NAME_LEN))
                                return -EFAULT;
                        copied++;
                }
                out_resp->count_enum_blobs = enum_count;
        }

        /*
         * NOTE: The idea seems to have been to use this to read all the blob
         * property values. But nothing ever added them to the corresponding
         * list, userspace always used the special-purpose get_blob ioctl to
         * read the value for a blob property. It also doesn't make a lot of
         * sense to return values here when everything else is just metadata for
         * the property itself.
         */
        if (drm_property_type_is(property, DRM_MODE_PROP_BLOB))
                out_resp->count_enum_blobs = 0;

        return 0;
}

static void drm_property_free_blob(struct kref *kref)
{
        struct drm_property_blob *blob =
                container_of(kref, struct drm_property_blob, base.refcount);

        mutex_lock(&blob->dev->mode_config.blob_lock);
        list_del(&blob->head_global);
        mutex_unlock(&blob->dev->mode_config.blob_lock);

        drm_mode_object_unregister(blob->dev, &blob->base);

        kvfree(blob);
}

/**
 * drm_property_create_blob - Create new blob property
 * @dev: DRM device to create property for
 * @length: Length to allocate for blob data
 * @data: If specified, copies data into blob
 *
 * Creates a new blob property for a specified DRM device, optionally
 * copying data. Note that blob properties are meant to be invariant, hence the
 * data must be filled out before the blob is used as the value of any property.
 *
 * Returns:
 * New blob property with a single reference on success, or an ERR_PTR
 * value on failure.
 */
struct drm_property_blob *
drm_property_create_blob(struct drm_device *dev, size_t length,
                         const void *data)
{
        struct drm_property_blob *blob;
        int ret;

        if (!length || length > ULONG_MAX - sizeof(struct drm_property_blob))
                return ERR_PTR(-EINVAL);

        blob = kvzalloc(sizeof(struct drm_property_blob)+length, GFP_KERNEL);
        if (!blob)
                return ERR_PTR(-ENOMEM);

        /* This must be explicitly initialised, so we can safely call list_del
         * on it in the removal handler, even if it isn't in a file list. */
        INIT_LIST_HEAD(&blob->head_file);
        blob->data = (void *)blob + sizeof(*blob);
        blob->length = length;
        blob->dev = dev;

        if (data)
                memcpy(blob->data, data, length);

        ret = __drm_mode_object_add(dev, &blob->base, DRM_MODE_OBJECT_BLOB,
                                    true, drm_property_free_blob);
        if (ret) {
                kvfree(blob);
                return ERR_PTR(-EINVAL);
        }

        mutex_lock(&dev->mode_config.blob_lock);
        list_add_tail(&blob->head_global,
                      &dev->mode_config.property_blob_list);
        mutex_unlock(&dev->mode_config.blob_lock);

        return blob;
}
EXPORT_SYMBOL(drm_property_create_blob);

/**
 * drm_property_blob_put - release a blob property reference
 * @blob: DRM blob property
 *
 * Releases a reference to a blob property. May free the object.
 */
void drm_property_blob_put(struct drm_property_blob *blob)
{
        if (!blob)
                return;

        drm_mode_object_put(&blob->base);
}
EXPORT_SYMBOL(drm_property_blob_put);

void drm_property_destroy_user_blobs(struct drm_device *dev,
                                     struct drm_file *file_priv)
{
        struct drm_property_blob *blob, *bt;

        /*
         * When the file gets released that means no one else can access the
         * blob list any more, so no need to grab dev->blob_lock.
         */
        list_for_each_entry_safe(blob, bt, &file_priv->blobs, head_file) {
                list_del_init(&blob->head_file);
                drm_property_blob_put(blob);
        }
}

/**
 * drm_property_blob_get - acquire blob property reference
 * @blob: DRM blob property
 *
 * Acquires a reference to an existing blob property. Returns @blob, which
 * allows this to be used as a shorthand in assignments.
 */
struct drm_property_blob *drm_property_blob_get(struct drm_property_blob *blob)
{
        drm_mode_object_get(&blob->base);
        return blob;
}
EXPORT_SYMBOL(drm_property_blob_get);

/**
 * drm_property_lookup_blob - look up a blob property and take a reference
 * @dev: drm device
 * @id: id of the blob property
 *
 * If successful, this takes an additional reference to the blob property.
 * callers need to make sure to eventually unreference the returned property
 * again, using drm_property_blob_put().
 *
 * Return:
 * NULL on failure, pointer to the blob on success.
 */
struct drm_property_blob *drm_property_lookup_blob(struct drm_device *dev,
                                                   uint32_t id)
{
        struct drm_mode_object *obj;
        struct drm_property_blob *blob = NULL;

        obj = __drm_mode_object_find(dev, NULL, id, DRM_MODE_OBJECT_BLOB);
        if (obj)
                blob = obj_to_blob(obj);
        return blob;
}
EXPORT_SYMBOL(drm_property_lookup_blob);

/**
 * drm_property_replace_global_blob - replace existing blob property
 * @dev: drm device
 * @replace: location of blob property pointer to be replaced
 * @length: length of data for new blob, or 0 for no data
 * @data: content for new blob, or NULL for no data
 * @obj_holds_id: optional object for property holding blob ID
 * @prop_holds_id: optional property holding blob ID
 * @return 0 on success or error on failure
 *
 * This function will replace a global property in the blob list, optionally
 * updating a property which holds the ID of that property.
 *
 * If length is 0 or data is NULL, no new blob will be created, and the holding
 * property, if specified, will be set to 0.
 *
 * Access to the replace pointer is assumed to be protected by the caller, e.g.
 * by holding the relevant modesetting object lock for its parent.
 *
 * For example, a drm_connector has a 'PATH' property, which contains the ID
 * of a blob property with the value of the MST path information. Calling this
 * function with replace pointing to the connector's path_blob_ptr, length and
 * data set for the new path information, obj_holds_id set to the connector's
 * base object, and prop_holds_id set to the path property name, will perform
 * a completely atomic update. The access to path_blob_ptr is protected by the
 * caller holding a lock on the connector.
 */
int drm_property_replace_global_blob(struct drm_device *dev,
                                     struct drm_property_blob **replace,
                                     size_t length,
                                     const void *data,
                                     struct drm_mode_object *obj_holds_id,
                                     struct drm_property *prop_holds_id)
{
        struct drm_property_blob *new_blob = NULL;
        struct drm_property_blob *old_blob = NULL;
        int ret;

        WARN_ON(replace == NULL);

        old_blob = *replace;

        if (length && data) {
                new_blob = drm_property_create_blob(dev, length, data);
                if (IS_ERR(new_blob))
                        return PTR_ERR(new_blob);
        }

        if (obj_holds_id) {
                ret = drm_object_property_set_value(obj_holds_id,
                                                    prop_holds_id,
                                                    new_blob ?
                                                        new_blob->base.id : 0);
                if (ret != 0)
                        goto err_created;
        }

        drm_property_blob_put(old_blob);
        *replace = new_blob;

        return 0;

err_created:
        drm_property_blob_put(new_blob);
        return ret;
}
EXPORT_SYMBOL(drm_property_replace_global_blob);

/**
 * drm_property_replace_blob - replace a blob property
 * @blob: a pointer to the member blob to be replaced
 * @new_blob: the new blob to replace with
 *
 * Return: true if the blob was in fact replaced.
 */
bool drm_property_replace_blob(struct drm_property_blob **blob,
                               struct drm_property_blob *new_blob)
{
        struct drm_property_blob *old_blob = *blob;

        if (old_blob == new_blob)
                return false;

        drm_property_blob_put(old_blob);
        if (new_blob)
                drm_property_blob_get(new_blob);
        *blob = new_blob;
        return true;
}
EXPORT_SYMBOL(drm_property_replace_blob);

int drm_mode_getblob_ioctl(struct drm_device *dev,
                           void *data, struct drm_file *file_priv)
{
        struct drm_mode_get_blob *out_resp = data;
        struct drm_property_blob *blob;
        int ret = 0;

        if (!drm_core_check_feature(dev, DRIVER_MODESET))
                return -EOPNOTSUPP;

        blob = drm_property_lookup_blob(dev, out_resp->blob_id);
        if (!blob)
                return -ENOENT;

        if (out_resp->length == blob->length) {
                if (copy_to_user(u64_to_user_ptr(out_resp->data),
                                 blob->data,
                                 blob->length)) {
                        ret = -EFAULT;
                        goto unref;
                }
        }
        out_resp->length = blob->length;
unref:
        drm_property_blob_put(blob);

        return ret;
}

int drm_mode_createblob_ioctl(struct drm_device *dev,
                              void *data, struct drm_file *file_priv)
{
        struct drm_mode_create_blob *out_resp = data;
        struct drm_property_blob *blob;
        int ret = 0;

        if (!drm_core_check_feature(dev, DRIVER_MODESET))
                return -EOPNOTSUPP;

        blob = drm_property_create_blob(dev, out_resp->length, NULL);
        if (IS_ERR(blob))
                return PTR_ERR(blob);

        if (copy_from_user(blob->data,
                           u64_to_user_ptr(out_resp->data),
                           out_resp->length)) {
                ret = -EFAULT;
                goto out_blob;
        }

        /* Dropping the lock between create_blob and our access here is safe
         * as only the same file_priv can remove the blob; at this point, it is
         * not associated with any file_priv. */
        mutex_lock(&dev->mode_config.blob_lock);
        out_resp->blob_id = blob->base.id;
        list_add_tail(&blob->head_file, &file_priv->blobs);
        mutex_unlock(&dev->mode_config.blob_lock);

        return 0;

out_blob:
        drm_property_blob_put(blob);
        return ret;
}

int drm_mode_destroyblob_ioctl(struct drm_device *dev,
                               void *data, struct drm_file *file_priv)
{
        struct drm_mode_destroy_blob *out_resp = data;
        struct drm_property_blob *blob = NULL, *bt;
        bool found = false;
        int ret = 0;

        if (!drm_core_check_feature(dev, DRIVER_MODESET))
                return -EOPNOTSUPP;

        blob = drm_property_lookup_blob(dev, out_resp->blob_id);
        if (!blob)
                return -ENOENT;

        mutex_lock(&dev->mode_config.blob_lock);
        /* Ensure the property was actually created by this user. */
        list_for_each_entry(bt, &file_priv->blobs, head_file) {
                if (bt == blob) {
                        found = true;
                        break;
                }
        }

        if (!found) {
                ret = -EPERM;
                goto err;
        }

        /* We must drop head_file here, because we may not be the last
         * reference on the blob. */
        list_del_init(&blob->head_file);
        mutex_unlock(&dev->mode_config.blob_lock);

        /* One reference from lookup, and one from the filp. */
        drm_property_blob_put(blob);
        drm_property_blob_put(blob);

        return 0;

err:
        mutex_unlock(&dev->mode_config.blob_lock);
        drm_property_blob_put(blob);

        return ret;
}

/* Some properties could refer to dynamic refcnt'd objects, or things that
 * need special locking to handle lifetime issues (ie. to ensure the prop
 * value doesn't become invalid part way through the property update due to
 * race).  The value returned by reference via 'obj' should be passed back
 * to drm_property_change_valid_put() after the property is set (and the
 * object to which the property is attached has a chance to take it's own
 * reference).
 */
bool drm_property_change_valid_get(struct drm_property *property,
                                   uint64_t value, struct drm_mode_object **ref)
{
        int i;

        if (property->flags & DRM_MODE_PROP_IMMUTABLE)
                return false;

        *ref = NULL;

        if (drm_property_type_is(property, DRM_MODE_PROP_RANGE)) {
                if (value < property->values[0] || value > property->values[1])
                        return false;
                return true;
        } else if (drm_property_type_is(property, DRM_MODE_PROP_SIGNED_RANGE)) {
                int64_t svalue = U642I64(value);

                if (svalue < U642I64(property->values[0]) ||
                                svalue > U642I64(property->values[1]))
                        return false;
                return true;
        } else if (drm_property_type_is(property, DRM_MODE_PROP_BITMASK)) {
                uint64_t valid_mask = 0;

                for (i = 0; i < property->num_values; i++)
                        valid_mask |= (1ULL << property->values[i]);
                return !(value & ~valid_mask);
        } else if (drm_property_type_is(property, DRM_MODE_PROP_BLOB)) {
                struct drm_property_blob *blob;

                if (value == 0)
                        return true;

                blob = drm_property_lookup_blob(property->dev, value);
                if (blob) {
                        *ref = &blob->base;
                        return true;
                } else {
                        return false;
                }
        } else if (drm_property_type_is(property, DRM_MODE_PROP_OBJECT)) {
                /* a zero value for an object property translates to null: */
                if (value == 0)
                        return true;

                *ref = __drm_mode_object_find(property->dev, NULL, value,
                                              property->values[0]);
                return *ref != NULL;
        }

        for (i = 0; i < property->num_values; i++)
                if (property->values[i] == value)
                        return true;
        return false;
}

void drm_property_change_valid_put(struct drm_property *property,
                struct drm_mode_object *ref)
{
        if (!ref)
                return;

        if (drm_property_type_is(property, DRM_MODE_PROP_OBJECT)) {
                drm_mode_object_put(ref);
        } else if (drm_property_type_is(property, DRM_MODE_PROP_BLOB))
                drm_property_blob_put(obj_to_blob(ref));
}