dma-buf: use the new iterator in dma_resv_poll

Simplify the code a bit.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211005113742.1101-10-christian.koenig@amd.com

drivers/dma-buf/dma-buf.c

@@ -209,43 +209,20 @@ static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 	dma_fence_put(fence);
 }
 
-static bool dma_buf_poll_shared(struct dma_resv *resv,
+static bool dma_buf_poll_add_cb(struct dma_resv *resv, bool write,
 				struct dma_buf_poll_cb_t *dcb)
 {
-	struct dma_resv_list *fobj = dma_resv_shared_list(resv);
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
-	int i, r;
-
-	if (!fobj)
-		return false;
-
-	for (i = 0; i < fobj->shared_count; ++i) {
-		fence = rcu_dereference_protected(fobj->shared[i],
-						  dma_resv_held(resv));
-		dma_fence_get(fence);
-		r = dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb);
-		if (!r)
-			return true;
-		dma_fence_put(fence);
-	}
-
-	return false;
-}
-
-static bool dma_buf_poll_excl(struct dma_resv *resv,
-			      struct dma_buf_poll_cb_t *dcb)
-{
-	struct dma_fence *fence = dma_resv_excl_fence(resv);
 	int r;
 
-	if (!fence)
-		return false;
-
+	dma_resv_for_each_fence(&cursor, resv, write, fence) {
 		dma_fence_get(fence);
 		r = dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb);
 		if (!r)
 			return true;
 		dma_fence_put(fence);
+	}
 
 	return false;
 }
@@ -282,8 +259,7 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
 		spin_unlock_irq(&dmabuf->poll.lock);
 
 		if (events & EPOLLOUT) {
-			if (!dma_buf_poll_shared(resv, dcb) &&
-			    !dma_buf_poll_excl(resv, dcb))
+			if (!dma_buf_poll_add_cb(resv, true, dcb))
 				/* No callback queued, wake up any other waiters */
 				dma_buf_poll_cb(NULL, &dcb->cb);
 			else
@@ -303,7 +279,7 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
 		spin_unlock_irq(&dmabuf->poll.lock);
 
 		if (events & EPOLLIN) {
-			if (!dma_buf_poll_excl(resv, dcb))
+			if (!dma_buf_poll_add_cb(resv, false, dcb))
 				/* No callback queued, wake up any other waiters */
 				dma_buf_poll_cb(NULL, &dcb->cb);
 			else