xdp: make __xdp_return() MP-agnostic

Currently, __xdp_return() takes pointer to the virtual memory to free
a buffer. Apart from that this sometimes provokes redundant
data <--> page conversions, taking data pointer effectively prevents
lots of XDP code to support non-page-backed buffers, as there's no
mapping for the non-host memory (data is always NULL).
Just convert it to always take netmem reference. For
xdp_return_{buff,frame*}(), this chops off one page_address() per each
frag and adds one virt_to_netmem() (same as virt_to_page()) per header
buffer. For __xdp_return() itself, it removes one virt_to_page() for
MEM_TYPE_PAGE_POOL and another one for MEM_TYPE_PAGE_ORDER0, adding
one page_address() for [not really common nowadays]
MEM_TYPE_PAGE_SHARED, but the main effect is that the abovementioned
functions won't die or memleak anymore if the frame has non-host memory
attached and will correctly free those.

Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://patch.msgid.link/20241211172649.761483-4-aleksander.lobakin@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

2 files changed, 22 insertions, 34 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index 6c036708634b..5fea874025d3 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4125,7 +4125,7 @@ static void bpf_xdp_shrink_data_zc(struct xdp_buff *xdp, int shrink,
 
 	if (release) {
 		xsk_buff_del_tail(zc_frag);
-		__xdp_return(NULL, mem_type, false, zc_frag);
+		__xdp_return(0, mem_type, false, zc_frag);
 	} else {
 		zc_frag->data_end -= shrink;
 	}
@@ -4142,11 +4142,8 @@ static bool bpf_xdp_shrink_data(struct xdp_buff *xdp, skb_frag_t *frag,
 		goto out;
 	}
 
-	if (release) {
-		struct page *page = skb_frag_page(frag);
-
-		__xdp_return(page_address(page), mem_type, false, NULL);
-	}
+	if (release)
+		__xdp_return(skb_frag_netmem(frag), mem_type, false, NULL);
 
 out:
 	return release;
diff --git a/net/core/xdp.c b/net/core/xdp.c
index d367571c5838..f1165a35411b 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -430,27 +430,25 @@ EXPORT_SYMBOL_GPL(xdp_rxq_info_attach_page_pool);
  * is used for those calls sites.  Thus, allowing for faster recycling
  * of xdp_frames/pages in those cases.
  */
-void __xdp_return(void *data, enum xdp_mem_type mem_type, bool napi_direct,
-		  struct xdp_buff *xdp)
+void __xdp_return(netmem_ref netmem, enum xdp_mem_type mem_type,
+		  bool napi_direct, struct xdp_buff *xdp)
 {
-	struct page *page;
-
 	switch (mem_type) {
 	case MEM_TYPE_PAGE_POOL:
-		page = virt_to_head_page(data);
+		netmem = netmem_compound_head(netmem);
 		if (napi_direct && xdp_return_frame_no_direct())
 			napi_direct = false;
 		/* No need to check ((page->pp_magic & ~0x3UL) == PP_SIGNATURE)
 		 * as mem->type knows this a page_pool page
 		 */
-		page_pool_put_full_page(page->pp, page, napi_direct);
+		page_pool_put_full_netmem(netmem_get_pp(netmem), netmem,
+					  napi_direct);
 		break;
 	case MEM_TYPE_PAGE_SHARED:
-		page_frag_free(data);
+		page_frag_free(__netmem_address(netmem));
 		break;
 	case MEM_TYPE_PAGE_ORDER0:
-		page = virt_to_page(data); /* Assumes order0 page*/
-		put_page(page);
+		put_page(__netmem_to_page(netmem));
 		break;
 	case MEM_TYPE_XSK_BUFF_POOL:
 		/* NB! Only valid from an xdp_buff! */
@@ -466,38 +464,34 @@ void __xdp_return(void *data, enum xdp_mem_type mem_type, bool napi_direct,
 void xdp_return_frame(struct xdp_frame *xdpf)
 {
 	struct skb_shared_info *sinfo;
-	int i;
 
 	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]);
+	for (u32 i = 0; i < sinfo->nr_frags; i++)
+		__xdp_return(skb_frag_netmem(&sinfo->frags[i]), xdpf->mem_type,
+			     false, NULL);
 
-		__xdp_return(page_address(page), xdpf->mem_type, false, NULL);
-	}
 out:
-	__xdp_return(xdpf->data, xdpf->mem_type, false, NULL);
+	__xdp_return(virt_to_netmem(xdpf->data), xdpf->mem_type, false, NULL);
 }
 EXPORT_SYMBOL_GPL(xdp_return_frame);
 
 void xdp_return_frame_rx_napi(struct xdp_frame *xdpf)
 {
 	struct skb_shared_info *sinfo;
-	int i;
 
 	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]);
+	for (u32 i = 0; i < sinfo->nr_frags; i++)
+		__xdp_return(skb_frag_netmem(&sinfo->frags[i]), xdpf->mem_type,
+			     true, NULL);
 
-		__xdp_return(page_address(page), xdpf->mem_type, true, NULL);
-	}
 out:
-	__xdp_return(xdpf->data, xdpf->mem_type, true, NULL);
+	__xdp_return(virt_to_netmem(xdpf->data), xdpf->mem_type, true, NULL);
 }
 EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
 
@@ -544,20 +538,17 @@ EXPORT_SYMBOL_GPL(xdp_return_frame_bulk);
 void xdp_return_buff(struct xdp_buff *xdp)
 {
 	struct skb_shared_info *sinfo;
-	int i;
 
 	if (likely(!xdp_buff_has_frags(xdp)))
 		goto out;
 
 	sinfo = xdp_get_shared_info_from_buff(xdp);
-	for (i = 0; i < sinfo->nr_frags; i++) {
-		struct page *page = skb_frag_page(&sinfo->frags[i]);
+	for (u32 i = 0; i < sinfo->nr_frags; i++)
+		__xdp_return(skb_frag_netmem(&sinfo->frags[i]),
+			     xdp->rxq->mem.type, true, xdp);
 
-		__xdp_return(page_address(page), xdp->rxq->mem.type, true,
-			     xdp);
-	}
 out:
-	__xdp_return(xdp->data, xdp->rxq->mem.type, true, xdp);
+	__xdp_return(virt_to_netmem(xdp->data), xdp->rxq->mem.type, true, xdp);
 }
 EXPORT_SYMBOL_GPL(xdp_return_buff);