/* SPDX-License-Identifier: GPL-2.0 OR MIT */
/**************************************************************************
 *
 * 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;

                reservation_object_unlock(bo->resv);
        }
}

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;
                ttm_bo_del_from_lru(bo);
        }
}

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->bdev->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);
                reservation_object_unlock(bo->resv);
        }
        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->bdev->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)) {
                        reservation_object_unlock(bo->resv);

                        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->num_shared)
                                continue;

                        ret = reservation_object_reserve_shared(bo->resv,
                                                                entry->num_shared);
                        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) {
                        if (intr) {
                                ret = ww_mutex_lock_slow_interruptible(&bo->resv->lock,
                                                                       ticket);
                        } else {
                                ww_mutex_lock_slow(&bo->resv->lock, ticket);
                                ret = 0;
                        }
                }

                if (!ret && entry->num_shared)
                        ret = reservation_object_reserve_shared(bo->resv,
                                                                entry->num_shared);

                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 dma_fence *fence)
{
        struct ttm_validate_buffer *entry;
        struct ttm_buffer_object *bo;
        struct ttm_bo_global *glob;
        struct ttm_bo_device *bdev;

        if (list_empty(list))
                return;

        bo = list_first_entry(list, struct ttm_validate_buffer, head)->bo;
        bdev = bo->bdev;
        glob = bo->bdev->glob;

        spin_lock(&glob->lru_lock);

        list_for_each_entry(entry, list, head) {
                bo = entry->bo;
                if (entry->num_shared)
                        reservation_object_add_shared_fence(bo->resv, fence);
                else
                        reservation_object_add_excl_fence(bo->resv, fence);
                ttm_bo_add_to_lru(bo);
                reservation_object_unlock(bo->resv);
        }
        spin_unlock(&glob->lru_lock);
        if (ticket)
                ww_acquire_fini(ticket);
}
EXPORT_SYMBOL(ttm_eu_fence_buffer_objects);