[Intel-gfx] [PATCH 03/26] dma-buf: use new iterator in dma_resv_copy_fences

Christian König
2021-09-16T12:00:30Z

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>
---
drivers/dma-buf/dma-resv.c | 81 +++++++++++++++-----------------------
1 file changed, 32 insertions(+), 49 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index bbf36a08ced0..91c040cb7d63 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -431,74 +431,57 @@ EXPORT_SYMBOL_GPL(dma_resv_walk_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;
+ rcu_read_lock();
+ dma_resv_for_each_fence_unlocked(dst, &cursor, true, f) {

- rcu_read_unlock();
+ if (cursor.is_first) {
+ 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;
- }
+ rcu_read_unlock();
+ list = dma_resv_list_alloc(cnt);
+ if (!list)
+ return -ENOMEM;

- dst_list->shared_count = 0;
- for (i = 0; i < src_list->shared_count; ++i) {
- struct dma_fence __rcu **dst;
- struct dma_fence *fence;
+ list->shared_count = 0;
+ rcu_read_lock();

- fence = rcu_dereference(src_list->shared[i]);
- if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
- &fence->flags))
- continue;
-
- if (!dma_fence_get_rcu(fence)) {
- dma_resv_list_free(dst_list);
- src_list = dma_resv_shared_list(src);
- goto retry;
+ } else {
+ list = NULL;
}
+ excl = NULL;
+ }

- if (dma_fence_is_signaled(fence)) {
- dma_fence_put(fence);
- continue;
- }
+ if (dma_resv_iter_is_exclusive(&cursor))
+ excl = f;
+ else
+ RCU_INIT_POINTER(list->shared[list->shared_count++], f);

- dst = &dst_list->shared[dst_list->shared_count++];
- rcu_assign_pointer(*dst, fence);
- }
- } else {
- dst_list = NULL;
+ /* Don't drop the reference */
+ f = 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);
-
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;
}
--
2.25.1