drm/ttm: Optimize ttm_eu_backoff_reservation

Avoid the ttm_bo_unreserve() spinlocks by calling
ttm_eu_backoff_reservation_locked under the lru spinlock.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jerome Glisse <j.glisse@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
index 201a71d111ec..7dcc6470e2f5 100644
--- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c
+++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
@@ -101,15 +101,16 @@ static int ttm_eu_wait_unreserved_locked(struct list_head *list,
 void ttm_eu_backoff_reservation(struct list_head *list)
 {
         struct ttm_validate_buffer *entry;
+        struct ttm_bo_global *glob;
 
-        list_for_each_entry(entry, list, head) {
-                struct ttm_buffer_object *bo = entry->bo;
-                if (!entry->reserved)
-                        continue;
+        if (list_empty(list))
+                return;
 
-                entry->reserved = false;
-                ttm_bo_unreserve(bo);
-        }
+        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);