Am 17.09.21 um 16:35 schrieb Daniel Vetter:
On Fri, Sep 17, 2021 at 02:34:50PM +0200, Christian König wrote:
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 | 86 ++++++++++++++++---------------------- 1 file changed, 35 insertions(+), 51 deletions(-)
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index a3c79a99fb44..406150dea5e4 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -426,74 +426,58 @@ EXPORT_SYMBOL_GPL(dma_resv_iter_walk); */ 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);
-retry:
- if (src_list) {
unsigned int shared_count = src_list->shared_count;rcu_read_unlock();
- list = NULL;
- excl = NULL;
dst_list = dma_resv_list_alloc(shared_count);if (!dst_list)return -ENOMEM;
- rcu_read_lock();
- dma_resv_iter_begin(&cursor, src, true);
- dma_resv_for_each_fence_unlocked(&cursor, f) {
rcu_read_lock();src_list = dma_resv_shared_list(src);if (!src_list || src_list->shared_count > shared_count) {kfree(dst_list);goto retry;}
if (cursor.is_first) {Maybe have a wrapper for this, like dma_resv_iter_is_reset or is_first or is_restart (my preference) with some nice docs that this returns true everytime we had to restart the sequence?
Exactly that's what I wanted to avoid since the is_first (or whatever) function should only be used inside of the dma_resv.c code.
On the other hand I can just make that static here and document that it should never be exported.
Christian.
Otherwise I fully agree, this is so much better with all the hairy restarting and get_rcu and test_bit shovelled away somewhere.
Either way (but I much prefer a wrapper for is_first):
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
dma_resv_list_free(list);dma_fence_put(excl);
dst_list->shared_count = 0;for (i = 0; i < src_list->shared_count; ++i) {struct dma_fence __rcu **dst;struct dma_fence *fence;
if (cursor.fences) {unsigned int cnt = cursor.fences->shared_count;
fence = rcu_dereference(src_list->shared[i]);if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,&fence->flags))continue;
rcu_read_unlock();list = dma_resv_list_alloc(cnt);if (!list) {dma_resv_iter_end(&cursor);return -ENOMEM;}
if (!dma_fence_get_rcu(fence)) {dma_resv_list_free(dst_list);src_list = dma_resv_shared_list(src);goto retry;}
list->shared_count = 0;rcu_read_lock();
if (dma_fence_is_signaled(fence)) {dma_fence_put(fence);continue;
} else {list = NULL; }
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);
dma_fence_get(f);if (dma_resv_iter_is_exclusive(&cursor))excl = f;elseRCU_INIT_POINTER(list->shared[list->shared_count++], f);- }
- dma_resv_iter_end(&cursor); 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