text: /**************************************************************************
   *
   * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
   * All Rights Reserved.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sub license, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice (including the
   * next paragraph) shall be included in all copies or substantial portions
   * of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
   * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
   * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
   * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
   * USE OR OTHER DEALINGS IN THE SOFTWARE.
   *
   **************************************************************************/
  
  #include <drm/ttm/ttm_execbuf_util.h>
  #include <drm/ttm/ttm_bo_driver.h>
  #include <drm/ttm/ttm_placement.h>
  #include <linux/wait.h>
  #include <linux/sched.h>
  #include <linux/module.h>
  
  static void ttm_eu_backoff_reservation_reverse(struct list_head *list,
  					      struct ttm_validate_buffer *entry)
  {
  	list_for_each_entry_continue_reverse(entry, list, head) {
  		struct ttm_buffer_object *bo = entry->bo;
  
  		__ttm_bo_unreserve(bo);
  	}
  }
  
  static void ttm_eu_del_from_lru_locked(struct list_head *list)
  {
  	struct ttm_validate_buffer *entry;
  
  	list_for_each_entry(entry, list, head) {
  		struct ttm_buffer_object *bo = entry->bo;
  		unsigned put_count = ttm_bo_del_from_lru(bo);
  
  		ttm_bo_list_ref_sub(bo, put_count, true);
  	}
  }
  
  void ttm_eu_backoff_reservation(struct ww_acquire_ctx *ticket,
  				struct list_head *list)
  {
  	struct ttm_validate_buffer *entry;
  	struct ttm_bo_global *glob;
  
  	if (list_empty(list))
  		return;
  
  	entry = list_first_entry(list, struct ttm_validate_buffer, head);
  	glob = entry->bo->glob;
  
  	spin_lock(&glob->lru_lock);
  	list_for_each_entry(entry, list, head) {
  		struct ttm_buffer_object *bo = entry->bo;
  
  		ttm_bo_add_to_lru(bo);
  		__ttm_bo_unreserve(bo);
  	}
  	spin_unlock(&glob->lru_lock);
  
  	if (ticket)
  		ww_acquire_fini(ticket);
  }
  EXPORT_SYMBOL(ttm_eu_backoff_reservation);
  
  /*
   * Reserve buffers for validation.
   *
   * If a buffer in the list is marked for CPU access, we back off and
   * wait for that buffer to become free for GPU access.
   *
   * If a buffer is reserved for another validation, the validator with
   * the highest validation sequence backs off and waits for that buffer
   * to become unreserved. This prevents deadlocks when validating multiple
   * buffers in different orders.
   */
  
  int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
  			   struct list_head *list, bool intr,
  			   struct list_head *dups)
  {
  	struct ttm_bo_global *glob;
  	struct ttm_validate_buffer *entry;
  	int ret;
  
  	if (list_empty(list))
  		return 0;
  
  	entry = list_first_entry(list, struct ttm_validate_buffer, head);
  	glob = entry->bo->glob;
  
  	if (ticket)
  		ww_acquire_init(ticket, &reservation_ww_class);
  
  	list_for_each_entry(entry, list, head) {
  		struct ttm_buffer_object *bo = entry->bo;
  
  		ret = __ttm_bo_reserve(bo, intr, (ticket == NULL), ticket);
  		if (!ret && unlikely(atomic_read(&bo->cpu_writers) > 0)) {
  			__ttm_bo_unreserve(bo);
  
  			ret = -EBUSY;
  
  		} else if (ret == -EALREADY && dups) {
  			struct ttm_validate_buffer *safe = entry;
  			entry = list_prev_entry(entry, head);
  			list_del(&safe->head);
  			list_add(&safe->head, dups);
  			continue;
  		}
  
  		if (!ret) {
  			if (!entry->shared)
  				continue;
  
  			ret = reservation_object_reserve_shared(bo->resv);
  			if (!ret)
  				continue;
  		}
  
  		/* uh oh, we lost out, drop every reservation and try
  		 * to only reserve this buffer, then start over if
  		 * this succeeds.
  		 */
  		ttm_eu_backoff_reservation_reverse(list, entry);
  
  		if (ret == -EDEADLK && intr) {
  			ret = ww_mutex_lock_slow_interruptible(&bo->resv->lock,
  							       ticket);
  		} else if (ret == -EDEADLK) {
  			ww_mutex_lock_slow(&bo->resv->lock, ticket);
  			ret = 0;
  		}
  
  		if (!ret && entry->shared)
  			ret = reservation_object_reserve_shared(bo->resv);
  
  		if (unlikely(ret != 0)) {
  			if (ret == -EINTR)
  				ret = -ERESTARTSYS;
  			if (ticket) {
  				ww_acquire_done(ticket);
  				ww_acquire_fini(ticket);
  			}
  			return ret;
  		}
  
  		/* move this item to the front of the list,
  		 * forces correct iteration of the loop without keeping track
  		 */
  		list_del(&entry->head);
  		list_add(&entry->head, list);
  	}
  
  	if (ticket)
  		ww_acquire_done(ticket);
  	spin_lock(&glob->lru_lock);
  	ttm_eu_del_from_lru_locked(list);
  	spin_unlock(&glob->lru_lock);
  	return 0;
  }
  EXPORT_SYMBOL(ttm_eu_reserve_buffers);
  
  void ttm_eu_fence_buffer_objects(struct ww_acquire_ctx *ticket,
  				 struct list_head *list, struct fence *fence)
  {
  	struct ttm_validate_buffer *entry;
  	struct ttm_buffer_object *bo;
  	struct ttm_bo_global *glob;
  	struct ttm_bo_device *bdev;
  	struct ttm_bo_driver *driver;
  
  	if (list_empty(list))
  		return;
  
  	bo = list_first_entry(list, struct ttm_validate_buffer, head)->bo;
  	bdev = bo->bdev;
  	driver = bdev->driver;
  	glob = bo->glob;
  
  	spin_lock(&glob->lru_lock);
  
  	list_for_each_entry(entry, list, head) {
  		bo = entry->bo;
  		if (entry->shared)
  			reservation_object_add_shared_fence(bo->resv, fence);
  		else
  			reservation_object_add_excl_fence(bo->resv, fence);
  		ttm_bo_add_to_lru(bo);
  		__ttm_bo_unreserve(bo);
  	}
  	spin_unlock(&glob->lru_lock);
  	if (ticket)
  		ww_acquire_fini(ticket);
  }
  EXPORT_SYMBOL(ttm_eu_fence_buffer_objects);
  