dma-buf: use new iterator in dma_resv_copy_fences

This makes the function much simpler since the complex
retry logic is now handled else where.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20211005113742.1101-5-christian.koenig@amd.com

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 3cbcf66..08e5b8c 100644 (file)
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -432,74 +432,54 @@ EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
  */
 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
 {
-       struct dma_resv_list *src_list, *dst_list;
-       struct dma_fence *old, *new;
-       unsigned int i;
+       struct dma_resv_iter cursor;
+       struct dma_resv_list *list;
+       struct dma_fence *f, *excl;
 
        dma_resv_assert_held(dst);
 
-       rcu_read_lock();
-       src_list = dma_resv_shared_list(src);
+       list = NULL;
+       excl = NULL;
 
-retry:
-       if (src_list) {
-               unsigned int shared_count = src_list->shared_count;
+       dma_resv_iter_begin(&cursor, src, true);
+       dma_resv_for_each_fence_unlocked(&cursor, f) {
 
-               rcu_read_unlock();
+               if (dma_resv_iter_is_restarted(&cursor)) {
+                       dma_resv_list_free(list);
+                       dma_fence_put(excl);
 
-               dst_list = dma_resv_list_alloc(shared_count);
-               if (!dst_list)
-                       return -ENOMEM;
+                       if (cursor.fences) {
+                               unsigned int cnt = cursor.fences->shared_count;
 
-               rcu_read_lock();
-               src_list = dma_resv_shared_list(src);
-               if (!src_list || src_list->shared_count > shared_count) {
-                       kfree(dst_list);
-                       goto retry;
-               }
-
-               dst_list->shared_count = 0;
-               for (i = 0; i < src_list->shared_count; ++i) {
-                       struct dma_fence __rcu **dst;
-                       struct dma_fence *fence;
+                               list = dma_resv_list_alloc(cnt);
+                               if (!list) {
+                                       dma_resv_iter_end(&cursor);
+                                       return -ENOMEM;
+                               }
 
-                       fence = rcu_dereference(src_list->shared[i]);
-                       if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
-                                    &fence->flags))
-                               continue;
+                               list->shared_count = 0;
 
-                       if (!dma_fence_get_rcu(fence)) {
-                               dma_resv_list_free(dst_list);
-                               src_list = dma_resv_shared_list(src);
-                               goto retry;
+                       } else {
+                               list = NULL;
                        }
-
-                       if (dma_fence_is_signaled(fence)) {
-                               dma_fence_put(fence);
-                               continue;
-                       }
-
-                       dst = &dst_list->shared[dst_list->shared_count++];
-                       rcu_assign_pointer(*dst, fence);
+                       excl = NULL;
                }
-       } else {
-               dst_list = NULL;
-       }
 
-       new = dma_fence_get_rcu_safe(&src->fence_excl);
-       rcu_read_unlock();
-
-       src_list = dma_resv_shared_list(dst);
-       old = dma_resv_excl_fence(dst);
+               dma_fence_get(f);
+               if (dma_resv_iter_is_exclusive(&cursor))
+                       excl = f;
+               else
+                       RCU_INIT_POINTER(list->shared[list->shared_count++], f);
+       }
+       dma_resv_iter_end(&cursor);
 
        write_seqcount_begin(&dst->seq);
-       /* write_seqcount_begin provides the necessary memory barrier */
-       RCU_INIT_POINTER(dst->fence_excl, new);
-       RCU_INIT_POINTER(dst->fence, dst_list);
+       excl = rcu_replace_pointer(dst->fence_excl, excl, dma_resv_held(dst));
+       list = rcu_replace_pointer(dst->fence, list, dma_resv_held(dst));
        write_seqcount_end(&dst->seq);
 
-       dma_resv_list_free(src_list);
-       dma_fence_put(old);
+       dma_resv_list_free(list);
+       dma_fence_put(excl);
 
        return 0;
 }