Merge branch 'skb_frag_fill_page_desc'

Yunsheng Lin says:

====================
net: introduce skb_frag_fill_page_desc()

Most users use __skb_frag_set_page()/skb_frag_off_set()/
skb_frag_size_set() to fill the page desc for a skb frag.
It does not make much sense to calling __skb_frag_set_page()
without calling skb_frag_off_set(), as the offset may depend
on whether the page is head page or tail page, so add
skb_frag_fill_page_desc() to fill the page desc for a skb
frag.

In the future, we can make sure the page in the frag is
head page of compound page or a base page, if not, we
may warn about that and convert the tail page to head
page and update the offset accordingly, if we see a warning
about that, we also fix the caller to fill the head page
in the frag. when the fixing is done, we may remove the
warning and converting.

In this way, we can remove the compound_head() or use
page_ref_*() like the below case:
https://elixir.bootlin.com/linux/latest/source/net/core/page_pool.c#L881
https://elixir.bootlin.com/linux/latest/source/include/linux/skbuff.h#L3383

It may also convert net stack to use the folio easier.

V1: repost with all the ack/review tags included.
RFC: remove a local variable as pointed out by Simon.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 18 insertions, 24 deletions

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index e79e3a415ca9..98143b86a9dd 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -1415,11 +1415,10 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 			}
 
 			frag = &sinfo->frags[sinfo->nr_frags++];
-			__skb_frag_set_page(frag, page);
 
 			data_len = min_t(u32, kattr->test.data_size_in - size,
 					 PAGE_SIZE);
-			skb_frag_size_set(frag, data_len);
+			skb_frag_fill_page_desc(frag, page, 0, data_len);
 
 			if (copy_from_user(page_address(page), data_in + size,
 					   data_len)) {
diff --git a/net/core/gro.c b/net/core/gro.c
index 2d84165cb4f1..6783a47a6136 100644
--- a/net/core/gro.c
+++ b/net/core/gro.c
@@ -239,9 +239,7 @@ int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
 
 		pinfo->nr_frags = nr_frags + 1 + skbinfo->nr_frags;
 
-		__skb_frag_set_page(frag, page);
-		skb_frag_off_set(frag, first_offset);
-		skb_frag_size_set(frag, first_size);
+		skb_frag_fill_page_desc(frag, page, first_offset, first_size);
 
 		memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
 		/* We dont need to clear skbinfo->nr_frags here */
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 760238196db1..f56b8d697014 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2785,14 +2785,17 @@ static void pktgen_finalize_skb(struct pktgen_dev *pkt_dev, struct sk_buff *skb,
 					break;
 			}
 			get_page(pkt_dev->page);
-			skb_frag_set_page(skb, i, pkt_dev->page);
-			skb_frag_off_set(&skb_shinfo(skb)->frags[i], 0);
+
 			/*last fragment, fill rest of data*/
 			if (i == (frags - 1))
-				skb_frag_size_set(&skb_shinfo(skb)->frags[i],
-				    (datalen < PAGE_SIZE ? datalen : PAGE_SIZE));
+				skb_frag_fill_page_desc(&skb_shinfo(skb)->frags[i],
+							pkt_dev->page, 0,
+							(datalen < PAGE_SIZE ?
+							 datalen : PAGE_SIZE));
 			else
-				skb_frag_size_set(&skb_shinfo(skb)->frags[i], frag_len);
+				skb_frag_fill_page_desc(&skb_shinfo(skb)->frags[i],
+							pkt_dev->page, 0, frag_len);
+
 			datalen -= skb_frag_size(&skb_shinfo(skb)->frags[i]);
 			skb->len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
 			skb->data_len += skb_frag_size(&skb_shinfo(skb)->frags[i]);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 01b48e68aca0..6724a84ebb09 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -4234,10 +4234,9 @@ static inline skb_frag_t skb_head_frag_to_page_desc(struct sk_buff *frag_skb)
 	struct page *page;
 
 	page = virt_to_head_page(frag_skb->head);
-	__skb_frag_set_page(&head_frag, page);
-	skb_frag_off_set(&head_frag, frag_skb->data -
-			 (unsigned char *)page_address(page));
-	skb_frag_size_set(&head_frag, skb_headlen(frag_skb));
+	skb_frag_fill_page_desc(&head_frag, page, frag_skb->data -
+				(unsigned char *)page_address(page),
+				skb_headlen(frag_skb));
 	return head_frag;
 }
 
diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index a7cc4f9faac2..daeff54bdbfa 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -268,9 +268,8 @@ static void tls_append_frag(struct tls_record_info *record,
 		skb_frag_size_add(frag, size);
 	} else {
 		++frag;
-		__skb_frag_set_page(frag, pfrag->page);
-		skb_frag_off_set(frag, pfrag->offset);
-		skb_frag_size_set(frag, size);
+		skb_frag_fill_page_desc(frag, pfrag->page, pfrag->offset,
+					size);
 		++record->num_frags;
 		get_page(pfrag->page);
 	}
@@ -357,9 +356,8 @@ static int tls_create_new_record(struct tls_offload_context_tx *offload_ctx,
 		return -ENOMEM;
 
 	frag = &record->frags[0];
-	__skb_frag_set_page(frag, pfrag->page);
-	skb_frag_off_set(frag, pfrag->offset);
-	skb_frag_size_set(frag, prepend_size);
+	skb_frag_fill_page_desc(frag, pfrag->page, pfrag->offset,
+				prepend_size);
 
 	get_page(pfrag->page);
 	pfrag->offset += prepend_size;
diff --git a/net/xfrm/xfrm_ipcomp.c b/net/xfrm/xfrm_ipcomp.c
index 80143360bf09..9c0fa0e1786a 100644
--- a/net/xfrm/xfrm_ipcomp.c
+++ b/net/xfrm/xfrm_ipcomp.c
@@ -74,14 +74,11 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
 		if (!page)
 			return -ENOMEM;
 
-		__skb_frag_set_page(frag, page);
-
 		len = PAGE_SIZE;
 		if (dlen < len)
 			len = dlen;
 
-		skb_frag_off_set(frag, 0);
-		skb_frag_size_set(frag, len);
+		skb_frag_fill_page_desc(frag, page, 0, len);
 		memcpy(skb_frag_address(frag), scratch, len);
 
 		skb->truesize += len;