1 files changed, 21 insertions, 2 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
index c7d323657798..7b90def15674 100644
--- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c
+++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
@@ -129,13 +129,17 @@ int ttm_eu_reserve_buffers(struct list_head *list)
         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++;
 
+retry:
         list_for_each_entry(entry, list, head) {
                 struct ttm_buffer_object *bo = entry->bo;
 
+                /* already slowpath reserved? */
+                if (entry->reserved)
+                        continue;
+
                 ret = ttm_bo_reserve_nolru(bo, true, true, true, val_seq);
                 switch (ret) {
                 case 0:
@@ -155,11 +159,26 @@ retry:
                         /* fallthrough */
                 case -EAGAIN:
                         ttm_eu_backoff_reservation_locked(list);
+
+                        /*
+                         * temporarily increase sequence number every retry,
+                         * to prevent us from seeing our old reservation
+                         * sequence when someone else reserved the buffer,
+                         * but hasn't updated the seq_valid/seqno members yet.
+                         */
+                        val_seq = entry->bo->bdev->val_seq++;
+
                         spin_unlock(&glob->lru_lock);
                         ttm_eu_list_ref_sub(list);
-                        ret = ttm_bo_wait_unreserved(bo, true);
+                        ret = ttm_bo_reserve_slowpath_nolru(bo, true, val_seq);
                         if (unlikely(ret != 0))
                                 return ret;
+                        spin_lock(&glob->lru_lock);
+                        entry->reserved = true;
+                        if (unlikely(atomic_read(&bo->cpu_writers) > 0)) {
+                                ret = -EBUSY;
+                                goto err;
+                        }
                         goto retry;
                 default:
                         goto err;