text: /*
   * 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_auth.h>
  #include <drm/drm_framebuffer.h>
  #include <drm/drm_atomic.h>
  #include <drm/drm_print.h>
  
  #include "drm_internal.h"
  #include "drm_crtc_internal.h"
  
  /**
   * DOC: overview
   *
   * Frame buffers are abstract memory objects that provide a source of pixels to
   * scanout to a CRTC. Applications explicitly request the creation of frame
   * buffers through the DRM_IOCTL_MODE_ADDFB(2) ioctls and receive an opaque
   * handle that can be passed to the KMS CRTC control, plane configuration and
   * page flip functions.
   *
   * Frame buffers rely on the underlying memory manager for allocating backing
   * storage. When creating a frame buffer applications pass a memory handle
   * (or a list of memory handles for multi-planar formats) through the
   * &struct drm_mode_fb_cmd2 argument. For drivers using GEM as their userspace
   * buffer management interface this would be a GEM handle.  Drivers are however
   * free to use their own backing storage object handles, e.g. vmwgfx directly
   * exposes special TTM handles to userspace and so expects TTM handles in the
   * create ioctl and not GEM handles.
   *
   * Framebuffers are tracked with &struct drm_framebuffer. They are published
   * using drm_framebuffer_init() - after calling that function userspace can use
   * and access the framebuffer object. The helper function
   * drm_helper_mode_fill_fb_struct() can be used to pre-fill the required
   * metadata fields.
   *
   * The lifetime of a drm framebuffer is controlled with a reference count,
   * drivers can grab additional references with drm_framebuffer_get() and drop
   * them again with drm_framebuffer_put(). For driver-private framebuffers for
   * which the last reference is never dropped (e.g. for the fbdev framebuffer
   * when the struct &struct drm_framebuffer is embedded into the fbdev helper
   * struct) drivers can manually clean up a framebuffer at module unload time
   * with drm_framebuffer_unregister_private(). But doing this is not
   * recommended, and it's better to have a normal free-standing &struct
   * drm_framebuffer.
   */
  
  int drm_framebuffer_check_src_coords(uint32_t src_x, uint32_t src_y,
  				     uint32_t src_w, uint32_t src_h,
  				     const struct drm_framebuffer *fb)
  {
  	unsigned int fb_width, fb_height;
  
  	fb_width = fb->width << 16;
  	fb_height = fb->height << 16;
  
  	/* Make sure source coordinates are inside the fb. */
  	if (src_w > fb_width ||
  	    src_x > fb_width - src_w ||
  	    src_h > fb_height ||
  	    src_y > fb_height - src_h) {
  		DRM_DEBUG_KMS("Invalid source coordinates "
  			      "%u.%06ux%u.%06u+%u.%06u+%u.%06u (fb %ux%u)\n",
  			      src_w >> 16, ((src_w & 0xffff) * 15625) >> 10,
  			      src_h >> 16, ((src_h & 0xffff) * 15625) >> 10,
  			      src_x >> 16, ((src_x & 0xffff) * 15625) >> 10,
  			      src_y >> 16, ((src_y & 0xffff) * 15625) >> 10,
  			      fb->width, fb->height);
  		return -ENOSPC;
  	}
  
  	return 0;
  }
  
  /**
   * drm_mode_addfb - add an FB to the graphics configuration
   * @dev: drm device for the ioctl
   * @or: pointer to request structure
   * @file_priv: drm file
   *
   * Add a new FB to the specified CRTC, given a user request. This is the
   * original addfb ioctl which only supported RGB formats.
   *
   * Called by the user via ioctl, or by an in-kernel client.
   *
   * Returns:
   * Zero on success, negative errno on failure.
   */
  int drm_mode_addfb(struct drm_device *dev, struct drm_mode_fb_cmd *or,
  		   struct drm_file *file_priv)
  {
  	struct drm_mode_fb_cmd2 r = {};
  	int ret;
  
  	/* convert to new format and call new ioctl */
  	r.fb_id = or->fb_id;
  	r.width = or->width;
  	r.height = or->height;
  	r.pitches[0] = or->pitch;
  	r.pixel_format = drm_mode_legacy_fb_format(or->bpp, or->depth);
  	r.handles[0] = or->handle;
  
  	if (r.pixel_format == DRM_FORMAT_XRGB2101010 &&
  	    dev->driver->driver_features & DRIVER_PREFER_XBGR_30BPP)
  		r.pixel_format = DRM_FORMAT_XBGR2101010;
  
  	ret = drm_mode_addfb2(dev, &r, file_priv);
  	if (ret)
  		return ret;
  
  	or->fb_id = r.fb_id;
  
  	return 0;
  }
  
  int drm_mode_addfb_ioctl(struct drm_device *dev,
  			 void *data, struct drm_file *file_priv)
  {
  	return drm_mode_addfb(dev, data, file_priv);
  }
  
  static int fb_plane_width(int width,
  			  const struct drm_format_info *format, int plane)
  {
  	if (plane == 0)
  		return width;
  
  	return DIV_ROUND_UP(width, format->hsub);
  }
  
  static int fb_plane_height(int height,
  			   const struct drm_format_info *format, int plane)
  {
  	if (plane == 0)
  		return height;
  
  	return DIV_ROUND_UP(height, format->vsub);
  }
  
  static int framebuffer_check(struct drm_device *dev,
  			     const struct drm_mode_fb_cmd2 *r)
  {
  	const struct drm_format_info *info;
  	int i;
  
  	/* check if the format is supported at all */
  	info = __drm_format_info(r->pixel_format & ~DRM_FORMAT_BIG_ENDIAN);
  	if (!info) {
  		struct drm_format_name_buf format_name;
  
  		DRM_DEBUG_KMS("bad framebuffer format %s\n",
  			      drm_get_format_name(r->pixel_format,
  						  &format_name));
  		return -EINVAL;
  	}
  
  	/* now let the driver pick its own format info */
  	info = drm_get_format_info(dev, r);
  
  	if (r->width == 0) {
  		DRM_DEBUG_KMS("bad framebuffer width %u\n", r->width);
  		return -EINVAL;
  	}
  
  	if (r->height == 0) {
  		DRM_DEBUG_KMS("bad framebuffer height %u\n", r->height);
  		return -EINVAL;
  	}
  
  	for (i = 0; i < info->num_planes; i++) {
  		unsigned int width = fb_plane_width(r->width, info, i);
  		unsigned int height = fb_plane_height(r->height, info, i);
  		unsigned int cpp = info->cpp[i];
  
  		if (!r->handles[i]) {
  			DRM_DEBUG_KMS("no buffer object handle for plane %d\n", i);
  			return -EINVAL;
  		}
  
  		if ((uint64_t) width * cpp > UINT_MAX)
  			return -ERANGE;
  
  		if ((uint64_t) height * r->pitches[i] + r->offsets[i] > UINT_MAX)
  			return -ERANGE;
  
  		if (r->pitches[i] < width * cpp) {
  			DRM_DEBUG_KMS("bad pitch %u for plane %d\n", r->pitches[i], i);
  			return -EINVAL;
  		}
  
  		if (r->modifier[i] && !(r->flags & DRM_MODE_FB_MODIFIERS)) {
  			DRM_DEBUG_KMS("bad fb modifier %llu for plane %d\n",
  				      r->modifier[i], i);
  			return -EINVAL;
  		}
  
  		if (r->flags & DRM_MODE_FB_MODIFIERS &&
  		    r->modifier[i] != r->modifier[0]) {
  			DRM_DEBUG_KMS("bad fb modifier %llu for plane %d\n",
  				      r->modifier[i], i);
  			return -EINVAL;
  		}
  
  		/* modifier specific checks: */
  		switch (r->modifier[i]) {
  		case DRM_FORMAT_MOD_SAMSUNG_64_32_TILE:
  			/* NOTE: the pitch restriction may be lifted later if it turns
  			 * out that no hw has this restriction:
  			 */
  			if (r->pixel_format != DRM_FORMAT_NV12 ||
  					width % 128 || height % 32 ||
  					r->pitches[i] % 128) {
  				DRM_DEBUG_KMS("bad modifier data for plane %d\n", i);
  				return -EINVAL;
  			}
  			break;
  
  		default:
  			break;
  		}
  	}
  
  	for (i = info->num_planes; i < 4; i++) {
  		if (r->modifier[i]) {
  			DRM_DEBUG_KMS("non-zero modifier for unused plane %d\n", i);
  			return -EINVAL;
  		}
  
  		/* Pre-FB_MODIFIERS userspace didn't clear the structs properly. */
  		if (!(r->flags & DRM_MODE_FB_MODIFIERS))
  			continue;
  
  		if (r->handles[i]) {
  			DRM_DEBUG_KMS("buffer object handle for unused plane %d\n", i);
  			return -EINVAL;
  		}
  
  		if (r->pitches[i]) {
  			DRM_DEBUG_KMS("non-zero pitch for unused plane %d\n", i);
  			return -EINVAL;
  		}
  
  		if (r->offsets[i]) {
  			DRM_DEBUG_KMS("non-zero offset for unused plane %d\n", i);
  			return -EINVAL;
  		}
  	}
  
  	return 0;
  }
  
  struct drm_framebuffer *
  drm_internal_framebuffer_create(struct drm_device *dev,
  				const struct drm_mode_fb_cmd2 *r,
  				struct drm_file *file_priv)
  {
  	struct drm_mode_config *config = &dev->mode_config;
  	struct drm_framebuffer *fb;
  	int ret;
  
  	if (r->flags & ~(DRM_MODE_FB_INTERLACED | DRM_MODE_FB_MODIFIERS)) {
  		DRM_DEBUG_KMS("bad framebuffer flags 0x%08x\n", r->flags);
  		return ERR_PTR(-EINVAL);
  	}
  
  	if ((config->min_width > r->width) || (r->width > config->max_width)) {
  		DRM_DEBUG_KMS("bad framebuffer width %d, should be >= %d && <= %d\n",
  			  r->width, config->min_width, config->max_width);
  		return ERR_PTR(-EINVAL);
  	}
  	if ((config->min_height > r->height) || (r->height > config->max_height)) {
  		DRM_DEBUG_KMS("bad framebuffer height %d, should be >= %d && <= %d\n",
  			  r->height, config->min_height, config->max_height);
  		return ERR_PTR(-EINVAL);
  	}
  
  	if (r->flags & DRM_MODE_FB_MODIFIERS &&
  	    !dev->mode_config.allow_fb_modifiers) {
  		DRM_DEBUG_KMS("driver does not support fb modifiers\n");
  		return ERR_PTR(-EINVAL);
  	}
  
  	ret = framebuffer_check(dev, r);
  	if (ret)
  		return ERR_PTR(ret);
  
  	fb = dev->mode_config.funcs->fb_create(dev, file_priv, r);
  	if (IS_ERR(fb)) {
  		DRM_DEBUG_KMS("could not create framebuffer\n");
  		return fb;
  	}
  
  	return fb;
  }
  
  /**
   * drm_mode_addfb2 - add an FB to the graphics configuration
   * @dev: drm device for the ioctl
   * @data: data pointer for the ioctl
   * @file_priv: drm file for the ioctl call
   *
   * Add a new FB to the specified CRTC, given a user request with format. This is
   * the 2nd version of the addfb ioctl, which supports multi-planar framebuffers
   * and uses fourcc codes as pixel format specifiers.
   *
   * Called by the user via ioctl.
   *
   * Returns:
   * Zero on success, negative errno on failure.
   */
  int drm_mode_addfb2(struct drm_device *dev,
  		    void *data, struct drm_file *file_priv)
  {
  	struct drm_mode_fb_cmd2 *r = data;
  	struct drm_framebuffer *fb;
  
  	if (!drm_core_check_feature(dev, DRIVER_MODESET))
  		return -EINVAL;
  
  	fb = drm_internal_framebuffer_create(dev, r, file_priv);
  	if (IS_ERR(fb))
  		return PTR_ERR(fb);
  
  	DRM_DEBUG_KMS("[FB:%d]\n", fb->base.id);
  	r->fb_id = fb->base.id;
  
  	/* Transfer ownership to the filp for reaping on close */
  	mutex_lock(&file_priv->fbs_lock);
  	list_add(&fb->filp_head, &file_priv->fbs);
  	mutex_unlock(&file_priv->fbs_lock);
  
  	return 0;
  }
  
  struct drm_mode_rmfb_work {
  	struct work_struct work;
  	struct list_head fbs;
  };
  
  static void drm_mode_rmfb_work_fn(struct work_struct *w)
  {
  	struct drm_mode_rmfb_work *arg = container_of(w, typeof(*arg), work);
  
  	while (!list_empty(&arg->fbs)) {
  		struct drm_framebuffer *fb =
  			list_first_entry(&arg->fbs, typeof(*fb), filp_head);
  
  		list_del_init(&fb->filp_head);
  		drm_framebuffer_remove(fb);
  	}
  }
  
  /**
   * drm_mode_rmfb - remove an FB from the configuration
   * @dev: drm device
   * @fb_id: id of framebuffer to remove
   * @file_priv: drm file
   *
   * Remove the specified FB.
   *
   * Called by the user via ioctl, or by an in-kernel client.
   *
   * Returns:
   * Zero on success, negative errno on failure.
   */
  int drm_mode_rmfb(struct drm_device *dev, u32 fb_id,
  		  struct drm_file *file_priv)
  {
  	struct drm_framebuffer *fb = NULL;
  	struct drm_framebuffer *fbl = NULL;
  	int found = 0;
  
  	if (!drm_core_check_feature(dev, DRIVER_MODESET))
  		return -EINVAL;
  
  	fb = drm_framebuffer_lookup(dev, file_priv, fb_id);
  	if (!fb)
  		return -ENOENT;
  
  	mutex_lock(&file_priv->fbs_lock);
  	list_for_each_entry(fbl, &file_priv->fbs, filp_head)
  		if (fb == fbl)
  			found = 1;
  	if (!found) {
  		mutex_unlock(&file_priv->fbs_lock);
  		goto fail_unref;
  	}
  
  	list_del_init(&fb->filp_head);
  	mutex_unlock(&file_priv->fbs_lock);
  
  	/* drop the reference we picked up in framebuffer lookup */
  	drm_framebuffer_put(fb);
  
  	/*
  	 * we now own the reference that was stored in the fbs list
  	 *
  	 * drm_framebuffer_remove may fail with -EINTR on pending signals,
  	 * so run this in a separate stack as there's no way to correctly
  	 * handle this after the fb is already removed from the lookup table.
  	 */
  	if (drm_framebuffer_read_refcount(fb) > 1) {
  		struct drm_mode_rmfb_work arg;
  
  		INIT_WORK_ONSTACK(&arg.work, drm_mode_rmfb_work_fn);
  		INIT_LIST_HEAD(&arg.fbs);
  		list_add_tail(&fb->filp_head, &arg.fbs);
  
  		schedule_work(&arg.work);
  		flush_work(&arg.work);
  		destroy_work_on_stack(&arg.work);
  	} else
  		drm_framebuffer_put(fb);
  
  	return 0;
  
  fail_unref:
  	drm_framebuffer_put(fb);
  	return -ENOENT;
  }
  
  int drm_mode_rmfb_ioctl(struct drm_device *dev,
  			void *data, struct drm_file *file_priv)
  {
  	uint32_t *fb_id = data;
  
  	return drm_mode_rmfb(dev, *fb_id, file_priv);
  }
  
  /**
   * drm_mode_getfb - get FB info
   * @dev: drm device for the ioctl
   * @data: data pointer for the ioctl
   * @file_priv: drm file for the ioctl call
   *
   * Lookup the FB given its ID and return info about it.
   *
   * Called by the user via ioctl.
   *
   * Returns:
   * Zero on success, negative errno on failure.
   */
  int drm_mode_getfb(struct drm_device *dev,
  		   void *data, struct drm_file *file_priv)
  {
  	struct drm_mode_fb_cmd *r = data;
  	struct drm_framebuffer *fb;
  	int ret;
  
  	if (!drm_core_check_feature(dev, DRIVER_MODESET))
  		return -EINVAL;
  
  	fb = drm_framebuffer_lookup(dev, file_priv, r->fb_id);
  	if (!fb)
  		return -ENOENT;
  
  	/* Multi-planar framebuffers need getfb2. */
  	if (fb->format->num_planes > 1) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	if (!fb->funcs->create_handle) {
  		ret = -ENODEV;
  		goto out;
  	}
  
  	r->height = fb->height;
  	r->width = fb->width;
  	r->depth = fb->format->depth;
  	r->bpp = fb->format->cpp[0] * 8;
  	r->pitch = fb->pitches[0];
  
  	/* GET_FB() is an unprivileged ioctl so we must not return a
  	 * buffer-handle to non-master processes! For
  	 * backwards-compatibility reasons, we cannot make GET_FB() privileged,
  	 * so just return an invalid handle for non-masters.
  	 */
  	if (!drm_is_current_master(file_priv) && !capable(CAP_SYS_ADMIN)) {
  		r->handle = 0;
  		ret = 0;
  		goto out;
  	}
  
  	ret = fb->funcs->create_handle(fb, file_priv, &r->handle);
  
  out:
  	drm_framebuffer_put(fb);
  
  	return ret;
  }
  
  /**
   * drm_mode_dirtyfb_ioctl - flush frontbuffer rendering on an FB
   * @dev: drm device for the ioctl
   * @data: data pointer for the ioctl
   * @file_priv: drm file for the ioctl call
   *
   * Lookup the FB and flush out the damaged area supplied by userspace as a clip
   * rectangle list. Generic userspace which does frontbuffer rendering must call
   * this ioctl to flush out the changes on manual-update display outputs, e.g.
   * usb display-link, mipi manual update panels or edp panel self refresh modes.
   *
   * Modesetting drivers which always update the frontbuffer do not need to
   * implement the corresponding &drm_framebuffer_funcs.dirty callback.
   *
   * Called by the user via ioctl.
   *
   * Returns:
   * Zero on success, negative errno on failure.
   */
  int drm_mode_dirtyfb_ioctl(struct drm_device *dev,
  			   void *data, struct drm_file *file_priv)
  {
  	struct drm_clip_rect __user *clips_ptr;
  	struct drm_clip_rect *clips = NULL;
  	struct drm_mode_fb_dirty_cmd *r = data;
  	struct drm_framebuffer *fb;
  	unsigned flags;
  	int num_clips;
  	int ret;
  
  	if (!drm_core_check_feature(dev, DRIVER_MODESET))
  		return -EINVAL;
  
  	fb = drm_framebuffer_lookup(dev, file_priv, r->fb_id);
  	if (!fb)
  		return -ENOENT;
  
  	num_clips = r->num_clips;
  	clips_ptr = (struct drm_clip_rect __user *)(unsigned long)r->clips_ptr;
  
  	if (!num_clips != !clips_ptr) {
  		ret = -EINVAL;
  		goto out_err1;
  	}
  
  	flags = DRM_MODE_FB_DIRTY_FLAGS & r->flags;
  
  	/* If userspace annotates copy, clips must come in pairs */
  	if (flags & DRM_MODE_FB_DIRTY_ANNOTATE_COPY && (num_clips % 2)) {
  		ret = -EINVAL;
  		goto out_err1;
  	}
  
  	if (num_clips && clips_ptr) {
  		if (num_clips < 0 || num_clips > DRM_MODE_FB_DIRTY_MAX_CLIPS) {
  			ret = -EINVAL;
  			goto out_err1;
  		}
  		clips = kcalloc(num_clips, sizeof(*clips), GFP_KERNEL);
  		if (!clips) {
  			ret = -ENOMEM;
  			goto out_err1;
  		}
  
  		ret = copy_from_user(clips, clips_ptr,
  				     num_clips * sizeof(*clips));
  		if (ret) {
  			ret = -EFAULT;
  			goto out_err2;
  		}
  	}
  
  	if (fb->funcs->dirty) {
  		ret = fb->funcs->dirty(fb, file_priv, flags, r->color,
  				       clips, num_clips);
  	} else {
  		ret = -ENOSYS;
  	}
  
  out_err2:
  	kfree(clips);
  out_err1:
  	drm_framebuffer_put(fb);
  
  	return ret;
  }
  
  /**
   * drm_fb_release - remove and free the FBs on this file
   * @priv: drm file for the ioctl
   *
   * Destroy all the FBs associated with @filp.
   *
   * Called by the user via ioctl.
   *
   * Returns:
   * Zero on success, negative errno on failure.
   */
  void drm_fb_release(struct drm_file *priv)
  {
  	struct drm_framebuffer *fb, *tfb;
  	struct drm_mode_rmfb_work arg;
  
  	INIT_LIST_HEAD(&arg.fbs);
  
  	/*
  	 * When the file gets released that means no one else can access the fb
  	 * list any more, so no need to grab fpriv->fbs_lock. And we need to
  	 * avoid upsetting lockdep since the universal cursor code adds a
  	 * framebuffer while holding mutex locks.
  	 *
  	 * Note that a real deadlock between fpriv->fbs_lock and the modeset
  	 * locks is impossible here since no one else but this function can get
  	 * at it any more.
  	 */
  	list_for_each_entry_safe(fb, tfb, &priv->fbs, filp_head) {
  		if (drm_framebuffer_read_refcount(fb) > 1) {
  			list_move_tail(&fb->filp_head, &arg.fbs);
  		} else {
  			list_del_init(&fb->filp_head);
  
  			/* This drops the fpriv->fbs reference. */
  			drm_framebuffer_put(fb);
  		}
  	}
  
  	if (!list_empty(&arg.fbs)) {
  		INIT_WORK_ONSTACK(&arg.work, drm_mode_rmfb_work_fn);
  
  		schedule_work(&arg.work);
  		flush_work(&arg.work);
  		destroy_work_on_stack(&arg.work);
  	}
  }
  
  void drm_framebuffer_free(struct kref *kref)
  {
  	struct drm_framebuffer *fb =
  			container_of(kref, struct drm_framebuffer, base.refcount);
  	struct drm_device *dev = fb->dev;
  
  	/*
  	 * The lookup idr holds a weak reference, which has not necessarily been
  	 * removed at this point. Check for that.
  	 */
  	drm_mode_object_unregister(dev, &fb->base);
  
  	fb->funcs->destroy(fb);
  }
  
  /**
   * drm_framebuffer_init - initialize a framebuffer
   * @dev: DRM device
   * @fb: framebuffer to be initialized
   * @funcs: ... with these functions
   *
   * Allocates an ID for the framebuffer's parent mode object, sets its mode
   * functions & device file and adds it to the master fd list.
   *
   * IMPORTANT:
   * This functions publishes the fb and makes it available for concurrent access
   * by other users. Which means by this point the fb _must_ be fully set up -
   * since all the fb attributes are invariant over its lifetime, no further
   * locking but only correct reference counting is required.
   *
   * Returns:
   * Zero on success, error code on failure.
   */
  int drm_framebuffer_init(struct drm_device *dev, struct drm_framebuffer *fb,
  			 const struct drm_framebuffer_funcs *funcs)
  {
  	int ret;
  
  	if (WARN_ON_ONCE(fb->dev != dev || !fb->format))
  		return -EINVAL;
  
  	INIT_LIST_HEAD(&fb->filp_head);
  
  	fb->funcs = funcs;
  	strcpy(fb->comm, current->comm);
  
  	ret = __drm_mode_object_add(dev, &fb->base, DRM_MODE_OBJECT_FB,
  				    false, drm_framebuffer_free);
  	if (ret)
  		goto out;
  
  	mutex_lock(&dev->mode_config.fb_lock);
  	dev->mode_config.num_fb++;
  	list_add(&fb->head, &dev->mode_config.fb_list);
  	mutex_unlock(&dev->mode_config.fb_lock);
  
  	drm_mode_object_register(dev, &fb->base);
  out:
  	return ret;
  }
  EXPORT_SYMBOL(drm_framebuffer_init);
  
  /**
   * drm_framebuffer_lookup - look up a drm framebuffer and grab a reference
   * @dev: drm device
   * @file_priv: drm file to check for lease against.
   * @id: id of the fb object
   *
   * If successful, this grabs an additional reference to the framebuffer -
   * callers need to make sure to eventually unreference the returned framebuffer
   * again, using drm_framebuffer_put().
   */
  struct drm_framebuffer *drm_framebuffer_lookup(struct drm_device *dev,
  					       struct drm_file *file_priv,
  					       uint32_t id)
  {
  	struct drm_mode_object *obj;
  	struct drm_framebuffer *fb = NULL;
  
  	obj = __drm_mode_object_find(dev, file_priv, id, DRM_MODE_OBJECT_FB);
  	if (obj)
  		fb = obj_to_fb(obj);
  	return fb;
  }
  EXPORT_SYMBOL(drm_framebuffer_lookup);
  
  /**
   * drm_framebuffer_unregister_private - unregister a private fb from the lookup idr
   * @fb: fb to unregister
   *
   * Drivers need to call this when cleaning up driver-private framebuffers, e.g.
   * those used for fbdev. Note that the caller must hold a reference of it's own,
   * i.e. the object may not be destroyed through this call (since it'll lead to a
   * locking inversion).
   *
   * NOTE: This function is deprecated. For driver-private framebuffers it is not
   * recommended to embed a framebuffer struct info fbdev struct, instead, a
   * framebuffer pointer is preferred and drm_framebuffer_put() should be called
   * when the framebuffer is to be cleaned up.
   */
  void drm_framebuffer_unregister_private(struct drm_framebuffer *fb)
  {
  	struct drm_device *dev;
  
  	if (!fb)
  		return;
  
  	dev = fb->dev;
  
  	/* Mark fb as reaped and drop idr ref. */
  	drm_mode_object_unregister(dev, &fb->base);
  }
  EXPORT_SYMBOL(drm_framebuffer_unregister_private);
  
  /**
   * drm_framebuffer_cleanup - remove a framebuffer object
   * @fb: framebuffer to remove
   *
   * Cleanup framebuffer. This function is intended to be used from the drivers
   * &drm_framebuffer_funcs.destroy callback. It can also be used to clean up
   * driver private framebuffers embedded into a larger structure.
   *
   * Note that this function does not remove the fb from active usage - if it is
   * still used anywhere, hilarity can ensue since userspace could call getfb on
   * the id and get back -EINVAL. Obviously no concern at driver unload time.
   *
   * Also, the framebuffer will not be removed from the lookup idr - for
   * user-created framebuffers this will happen in in the rmfb ioctl. For
   * driver-private objects (e.g. for fbdev) drivers need to explicitly call
   * drm_framebuffer_unregister_private.
   */
  void drm_framebuffer_cleanup(struct drm_framebuffer *fb)
  {
  	struct drm_device *dev = fb->dev;
  
  	mutex_lock(&dev->mode_config.fb_lock);
  	list_del(&fb->head);
  	dev->mode_config.num_fb--;
  	mutex_unlock(&dev->mode_config.fb_lock);
  }
  EXPORT_SYMBOL(drm_framebuffer_cleanup);
  
  static int atomic_remove_fb(struct drm_framebuffer *fb)
  {
  	struct drm_modeset_acquire_ctx ctx;
  	struct drm_device *dev = fb->dev;
  	struct drm_atomic_state *state;
  	struct drm_plane *plane;
  	struct drm_connector *conn;
  	struct drm_connector_state *conn_state;
  	int i, ret;
  	unsigned plane_mask;
  	bool disable_crtcs = false;
  
  retry_disable:
  	drm_modeset_acquire_init(&ctx, 0);
  
  	state = drm_atomic_state_alloc(dev);
  	if (!state) {
  		ret = -ENOMEM;
  		goto out;
  	}
  	state->acquire_ctx = &ctx;
  
  retry:
  	plane_mask = 0;
  	ret = drm_modeset_lock_all_ctx(dev, &ctx);
  	if (ret)
  		goto unlock;
  
  	drm_for_each_plane(plane, dev) {
  		struct drm_plane_state *plane_state;
  
  		if (plane->state->fb != fb)
  			continue;
  
  		plane_state = drm_atomic_get_plane_state(state, plane);
  		if (IS_ERR(plane_state)) {
  			ret = PTR_ERR(plane_state);
  			goto unlock;
  		}
  
  		if (disable_crtcs && plane_state->crtc->primary == plane) {
  			struct drm_crtc_state *crtc_state;
  
  			crtc_state = drm_atomic_get_existing_crtc_state(state, plane_state->crtc);
  
  			ret = drm_atomic_add_affected_connectors(state, plane_state->crtc);
  			if (ret)
  				goto unlock;
  
  			crtc_state->active = false;
  			ret = drm_atomic_set_mode_for_crtc(crtc_state, NULL);
  			if (ret)
  				goto unlock;
  		}
  
  		drm_atomic_set_fb_for_plane(plane_state, NULL);
  		ret = drm_atomic_set_crtc_for_plane(plane_state, NULL);
  		if (ret)
  			goto unlock;
  
  		plane_mask |= drm_plane_mask(plane);
  	}
  
  	/* This list is only filled when disable_crtcs is set. */
  	for_each_new_connector_in_state(state, conn, conn_state, i) {
  		ret = drm_atomic_set_crtc_for_connector(conn_state, NULL);
  
  		if (ret)
  			goto unlock;
  	}
  
  	if (plane_mask)
  		ret = drm_atomic_commit(state);
  
  unlock:
  	if (ret == -EDEADLK) {
  		drm_atomic_state_clear(state);
  		drm_modeset_backoff(&ctx);
  		goto retry;
  	}
  
  	drm_atomic_state_put(state);
  
  out:
  	drm_modeset_drop_locks(&ctx);
  	drm_modeset_acquire_fini(&ctx);
  
  	if (ret == -EINVAL && !disable_crtcs) {
  		disable_crtcs = true;
  		goto retry_disable;
  	}
  
  	return ret;
  }
  
  static void legacy_remove_fb(struct drm_framebuffer *fb)
  {
  	struct drm_device *dev = fb->dev;
  	struct drm_crtc *crtc;
  	struct drm_plane *plane;
  
  	drm_modeset_lock_all(dev);
  	/* remove from any CRTC */
  	drm_for_each_crtc(crtc, dev) {
  		if (crtc->primary->fb == fb) {
  			/* should turn off the crtc */
  			if (drm_crtc_force_disable(crtc))
  				DRM_ERROR("failed to reset crtc %p when fb was deleted\n", crtc);
  		}
  	}
  
  	drm_for_each_plane(plane, dev) {
  		if (plane->fb == fb)
  			drm_plane_force_disable(plane);
  	}
  	drm_modeset_unlock_all(dev);
  }
  
  /**
   * drm_framebuffer_remove - remove and unreference a framebuffer object
   * @fb: framebuffer to remove
   *
   * Scans all the CRTCs and planes in @dev's mode_config.  If they're
   * using @fb, removes it, setting it to NULL. Then drops the reference to the
   * passed-in framebuffer. Might take the modeset locks.
   *
   * Note that this function optimizes the cleanup away if the caller holds the
   * last reference to the framebuffer. It is also guaranteed to not take the
   * modeset locks in this case.
   */
  void drm_framebuffer_remove(struct drm_framebuffer *fb)
  {
  	struct drm_device *dev;
  
  	if (!fb)
  		return;
  
  	dev = fb->dev;
  
  	WARN_ON(!list_empty(&fb->filp_head));
  
  	/*
  	 * drm ABI mandates that we remove any deleted framebuffers from active
  	 * useage. But since most sane clients only remove framebuffers they no
  	 * longer need, try to optimize this away.
  	 *
  	 * Since we're holding a reference ourselves, observing a refcount of 1
  	 * means that we're the last holder and can skip it. Also, the refcount
  	 * can never increase from 1 again, so we don't need any barriers or
  	 * locks.
  	 *
  	 * Note that userspace could try to race with use and instate a new
  	 * usage _after_ we've cleared all current ones. End result will be an
  	 * in-use fb with fb-id == 0. Userspace is allowed to shoot its own foot
  	 * in this manner.
  	 */
  	if (drm_framebuffer_read_refcount(fb) > 1) {
  		if (drm_drv_uses_atomic_modeset(dev)) {
  			int ret = atomic_remove_fb(fb);
  			WARN(ret, "atomic remove_fb failed with %i\n", ret);
  		} else
  			legacy_remove_fb(fb);
  	}
  
  	drm_framebuffer_put(fb);
  }
  EXPORT_SYMBOL(drm_framebuffer_remove);
  
  /**
   * drm_framebuffer_plane_width - width of the plane given the first plane
   * @width: width of the first plane
   * @fb: the framebuffer
   * @plane: plane index
   *
   * Returns:
   * The width of @plane, given that the width of the first plane is @width.
   */
  int drm_framebuffer_plane_width(int width,
  				const struct drm_framebuffer *fb, int plane)
  {
  	if (plane >= fb->format->num_planes)
  		return 0;
  
  	return fb_plane_width(width, fb->format, plane);
  }
  EXPORT_SYMBOL(drm_framebuffer_plane_width);
  
  /**
   * drm_framebuffer_plane_height - height of the plane given the first plane
   * @height: height of the first plane
   * @fb: the framebuffer
   * @plane: plane index
   *
   * Returns:
   * The height of @plane, given that the height of the first plane is @height.
   */
  int drm_framebuffer_plane_height(int height,
  				 const struct drm_framebuffer *fb, int plane)
  {
  	if (plane >= fb->format->num_planes)
  		return 0;
  
  	return fb_plane_height(height, fb->format, plane);
  }
  EXPORT_SYMBOL(drm_framebuffer_plane_height);
  
  void drm_framebuffer_print_info(struct drm_printer *p, unsigned int indent,
  				const struct drm_framebuffer *fb)
  {
  	struct drm_format_name_buf format_name;
  	unsigned int i;
  
  	drm_printf_indent(p, indent, "allocated by = %s\n", fb->comm);
  	drm_printf_indent(p, indent, "refcount=%u\n",
  			  drm_framebuffer_read_refcount(fb));
  	drm_printf_indent(p, indent, "format=%s\n",
  			  drm_get_format_name(fb->format->format, &format_name));
  	drm_printf_indent(p, indent, "modifier=0x%llx\n", fb->modifier);
  	drm_printf_indent(p, indent, "size=%ux%u\n", fb->width, fb->height);
  	drm_printf_indent(p, indent, "layers:\n");
  
  	for (i = 0; i < fb->format->num_planes; i++) {
  		drm_printf_indent(p, indent + 1, "size[%u]=%dx%d\n", i,
  				  drm_framebuffer_plane_width(fb->width, fb, i),
  				  drm_framebuffer_plane_height(fb->height, fb, i));
  		drm_printf_indent(p, indent + 1, "pitch[%u]=%u\n", i, fb->pitches[i]);
  		drm_printf_indent(p, indent + 1, "offset[%u]=%u\n", i, fb->offsets[i]);
  		drm_printf_indent(p, indent + 1, "obj[%u]:%s\n", i,
  				  fb->obj[i] ? "" : "(null)");
  		if (fb->obj[i])
  			drm_gem_print_info(p, indent + 2, fb->obj[i]);
  	}
  }
  
  #ifdef CONFIG_DEBUG_FS
  static int drm_framebuffer_info(struct seq_file *m, void *data)
  {
  	struct drm_info_node *node = m->private;
  	struct drm_device *dev = node->minor->dev;
  	struct drm_printer p = drm_seq_file_printer(m);
  	struct drm_framebuffer *fb;
  
  	mutex_lock(&dev->mode_config.fb_lock);
  	drm_for_each_fb(fb, dev) {
  		drm_printf(&p, "framebuffer[%u]:\n", fb->base.id);
  		drm_framebuffer_print_info(&p, 1, fb);
  	}
  	mutex_unlock(&dev->mode_config.fb_lock);
  
  	return 0;
  }
  
  static const struct drm_info_list drm_framebuffer_debugfs_list[] = {
  	{ "framebuffer", drm_framebuffer_info, 0 },
  };
  
  int drm_framebuffer_debugfs_init(struct drm_minor *minor)
  {
  	return drm_debugfs_create_files(drm_framebuffer_debugfs_list,
  				ARRAY_SIZE(drm_framebuffer_debugfs_list),
  				minor->debugfs_root, minor);
  }
  #endif
  