ttm_execbuf_util.c

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/**************************************************************************
 *
 * 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_locked(struct list_head *list)
{
    struct ttm_validate_buffer *entry;

    list_for_each_entry(entry, list, head) {
        struct ttm_buffer_object *bo = entry->bo;
        if (!entry->reserved)
            continue;

        if (entry->removed) {
            ttm_bo_add_to_lru(bo);
            entry->removed = false;

        }
        entry->reserved = false;
        atomic_set(&bo->reserved, 0);
        wake_up_all(&bo->event_queue);
    }
}

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;
        if (!entry->reserved)
            continue;

        if (!entry->removed) {
            entry->put_count = ttm_bo_del_from_lru(bo);
            entry->removed = true;
        }
    }
}

static void ttm_eu_list_ref_sub(struct list_head *list)
{
    struct ttm_validate_buffer *entry;

    list_for_each_entry(entry, list, head) {
        struct ttm_buffer_object *bo = entry->bo;

        if (entry->put_count) {
            ttm_bo_list_ref_sub(bo, entry->put_count, true);
            entry->put_count = 0;
        }
    }
}

static int ttm_eu_wait_unreserved_locked(struct list_head *list,
                     struct ttm_buffer_object *bo)
{
    struct ttm_bo_global *glob = bo->glob;
    int ret;

    ttm_eu_del_from_lru_locked(list);
    spin_unlock(&glob->lru_lock);
    ret = ttm_bo_wait_unreserved(bo, true);
    spin_lock(&glob->lru_lock);
    if (unlikely(ret != 0))
        ttm_eu_backoff_reservation_locked(list);
    return ret;
}


void ttm_eu_backoff_reservation(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);
    ttm_eu_backoff_reservation_locked(list);
    spin_unlock(&glob->lru_lock);
}
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 list_head *list)
{
    struct ttm_bo_global *glob;
    struct ttm_validate_buffer *entry;
    int ret;
    uint32_t val_seq;

    if (list_empty(list))
        return 0;

    list_for_each_entry(entry, list, head) {
        entry->reserved = false;
        entry->put_count = 0;
        entry->removed = false;
    }

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

retry:
    spin_lock(&glob->lru_lock);
    val_seq = entry->bo->bdev->val_seq++;

    list_for_each_entry(entry, list, head) {
        struct ttm_buffer_object *bo = entry->bo;

retry_this_bo:
        ret = ttm_bo_reserve_locked(bo, true, true, true, val_seq);
        switch (ret) {
        case 0:
            break;
        case -EBUSY:
            ret = ttm_eu_wait_unreserved_locked(list, bo);
            if (unlikely(ret != 0)) {
                spin_unlock(&glob->lru_lock);
                ttm_eu_list_ref_sub(list);
                return ret;
            }
            goto retry_this_bo;
        case -EAGAIN:
            ttm_eu_backoff_reservation_locked(list);
            spin_unlock(&glob->lru_lock);
            ttm_eu_list_ref_sub(list);
            ret = ttm_bo_wait_unreserved(bo, true);
            if (unlikely(ret != 0))
                return ret;
            goto retry;
        default:
            ttm_eu_backoff_reservation_locked(list);
            spin_unlock(&glob->lru_lock);
            ttm_eu_list_ref_sub(list);
            return ret;
        }

        entry->reserved = true;
        if (unlikely(atomic_read(&bo->cpu_writers) > 0)) {
            ttm_eu_backoff_reservation_locked(list);
            spin_unlock(&glob->lru_lock);
            ttm_eu_list_ref_sub(list);
            ret = ttm_bo_wait_cpu(bo, false);
            if (ret)
                return ret;
            goto retry;
        }
    }

    ttm_eu_del_from_lru_locked(list);
    spin_unlock(&glob->lru_lock);
    ttm_eu_list_ref_sub(list);

    return 0;
}
EXPORT_SYMBOL(ttm_eu_reserve_buffers);

void ttm_eu_fence_buffer_objects(struct list_head *list, void *sync_obj)
{
    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(&bdev->fence_lock);
    spin_lock(&glob->lru_lock);

    list_for_each_entry(entry, list, head) {
        bo = entry->bo;
        entry->old_sync_obj = bo->sync_obj;
        bo->sync_obj = driver->sync_obj_ref(sync_obj);
        bo->sync_obj_arg = entry->new_sync_obj_arg;
        ttm_bo_unreserve_locked(bo);
        entry->reserved = false;
    }
    spin_unlock(&glob->lru_lock);
    spin_unlock(&bdev->fence_lock);

    list_for_each_entry(entry, list, head) {
        if (entry->old_sync_obj)
            driver->sync_obj_unref(&entry->old_sync_obj);
    }
}
EXPORT_SYMBOL(ttm_eu_fence_buffer_objects);