drm/ttm: cleanup ttm_eu_reserve_buffers handling

With the lru lock no longer required for protecting reservations we
can just do a ttm_bo_reserve_nolru on -EBUSY, and handle all errors
in a single path.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>

1 files changed, 21 insertions, 32 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
index bd37b5cb8553..c7d323657798 100644
--- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c
+++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
@@ -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 +136,23 @@ retry:
         list_for_each_entry(entry, list, head) {
                 struct ttm_buffer_object *bo = entry->bo;
 
-retry_this_bo:
                 ret = ttm_bo_reserve_nolru(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;
+                        ttm_eu_del_from_lru_locked(list);
+                        spin_unlock(&glob->lru_lock);
+                        ret = ttm_bo_reserve_nolru(bo, true, false,
+                                                   true, val_seq);
+                        spin_lock(&glob->lru_lock);
+                        if (!ret)
+                                break;
+
+                        if (unlikely(ret != -EAGAIN))
+                                goto err;
+
+                        /* fallthrough */
                 case -EAGAIN:
                         ttm_eu_backoff_reservation_locked(list);
                         spin_unlock(&glob->lru_lock);
@@ -174,18 +162,13 @@ retry_this_bo:
                                 return ret;
                         goto retry;
                 default:
-                        ttm_eu_backoff_reservation_locked(list);
-                        spin_unlock(&glob->lru_lock);
-                        ttm_eu_list_ref_sub(list);
-                        return ret;
+                        goto err;
                 }
 
                 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);
-                        return -EBUSY;
+                        ret = -EBUSY;
+                        goto err;
                 }
         }
 
@@ -194,6 +177,12 @@ retry_this_bo:
         ttm_eu_list_ref_sub(list);
 
         return 0;
+
+err:
+        ttm_eu_backoff_reservation_locked(list);
+        spin_unlock(&glob->lru_lock);
+        ttm_eu_list_ref_sub(list);
+        return ret;
 }
 EXPORT_SYMBOL(ttm_eu_reserve_buffers);