xdp: remove unused {__,}xdp_release_frame()

__xdp_build_skb_from_frame() was the last user of
{__,}xdp_release_frame(), which detaches pages from the page_pool.
All the consumers now recycle Page Pool skbs and page, except mlx5,
stmmac and tsnep drivers, which use page_pool_release_page() directly
(might change one day). It's safe to assume this functionality is not
needed anymore and can be removed (in favor of recycling).
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://lore.kernel.org/r/20230313215553.1045175-5-aleksander.lobakin@intel.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

include/net/xdp.h

@@ -317,35 +317,6 @@ void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq);
 void xdp_return_frame_bulk(struct xdp_frame *xdpf,
 			   struct xdp_frame_bulk *bq);
 
-/* When sending xdp_frame into the network stack, then there is no
- * return point callback, which is needed to release e.g. DMA-mapping
- * resources with page_pool.  Thus, have explicit function to release
- * frame resources.
- */
-void __xdp_release_frame(void *data, struct xdp_mem_info *mem);
-static inline void xdp_release_frame(struct xdp_frame *xdpf)
-{
-	struct xdp_mem_info *mem = &xdpf->mem;
-	struct skb_shared_info *sinfo;
-	int i;
-
-	/* Curr only page_pool needs this */
-	if (mem->type != MEM_TYPE_PAGE_POOL)
-		return;
-
-	if (likely(!xdp_frame_has_frags(xdpf)))
-		goto out;
-
-	sinfo = xdp_get_shared_info_from_frame(xdpf);
-	for (i = 0; i < sinfo->nr_frags; i++) {
-		struct page *page = skb_frag_page(&sinfo->frags[i]);
-
-		__xdp_release_frame(page_address(page), mem);
-	}
-out:
-	__xdp_release_frame(xdpf->data, mem);
-}
-
 static __always_inline unsigned int xdp_get_frame_len(struct xdp_frame *xdpf)
 {
 	struct skb_shared_info *sinfo;

net/core/xdp.c

@@ -531,21 +531,6 @@ void xdp_return_buff(struct xdp_buff *xdp)
 }
 EXPORT_SYMBOL_GPL(xdp_return_buff);
 
-/* Only called for MEM_TYPE_PAGE_POOL see xdp.h */
-void __xdp_release_frame(void *data, struct xdp_mem_info *mem)
-{
-	struct xdp_mem_allocator *xa;
-	struct page *page;
-
-	rcu_read_lock();
-	xa = rhashtable_lookup(mem_id_ht, &mem->id, mem_id_rht_params);
-	page = virt_to_head_page(data);
-	if (xa)
-		page_pool_release_page(xa->page_pool, page);
-	rcu_read_unlock();
-}
-EXPORT_SYMBOL_GPL(__xdp_release_frame);
-
 void xdp_attachment_setup(struct xdp_attachment_info *info,
 			  struct netdev_bpf *bpf)
 {