drm/ttm: remove EBUSY handling in ttm_execbuf_util

How is this different from just calling with no_wait == false? As far as I can tell, both paths end up with the same result..

Signed-off-by Maarten Lankhorst <[email protected]>

drivers/gpu/drm/ttm/ttm_execbuf_util.c +1 -26

index 3f48a46..4e7b596 100644
@@ -82,22 +82,6 @@ static void ttm_eu_list_ref_sub(struct list_head *list)
        }
 }
 
-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;

@@ -152,19 +136,10 @@ retry:
        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);
+               ret = ttm_bo_reserve_locked(bo, true, false, 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);

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Quoted 4 lines · Maarten Lankhorst

How is this different from just calling with no_wait == false? As far as I can tell, both paths end up with the same result..

Signed-off-by Maarten Lankhorst <[email protected]>

NAK this seriously modify the behavior. The ttm_eu_del_from_lru_locked part is important. It must happen with lru lock held and without any dropping of this lock prior to wait for bo unreserve.

Hey,

Op 20-08-12 17:15, Jerome Glisse schreef:

Quoted 10 lines

Quoted 4 lines · Maarten Lankhorst

How is this different from just calling with no_wait == false? As far as I can tell, both paths end up with the same result..

Signed-off-by Maarten Lankhorst <[email protected]>

NAK this seriously modify the behavior. The ttm_eu_del_from_lru_locked part is important. It must happen with lru lock held and without any dropping of this lock prior to wait for bo unreserve.

You're right, I missed the part where it removed those, causing the later patch to be wrong too. However I still think the code can be made more readable. Wouldn't it be better if it used the unlocked variants instead? It would save a lot of extra list traversals, and you could drop removed, reserved and put_count from ttm_validate_buffer.

~Maarten