net: gro: move skb_gro_receive into net/core/gro.c

net/core/gro.c will contain all core gro functions,
to shrink net/core/skbuff.c and net/core/dev.c

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 118 insertions, 0 deletions

diff --git a/net/core/gro.c b/net/core/gro.c
new file mode 100644
index 000000000000..91a74c4da9ff
--- /dev/null
+++ b/net/core/gro.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <net/gro.h>
+
+int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
+{
+	struct skb_shared_info *pinfo, *skbinfo = skb_shinfo(skb);
+	unsigned int offset = skb_gro_offset(skb);
+	unsigned int headlen = skb_headlen(skb);
+	unsigned int len = skb_gro_len(skb);
+	unsigned int delta_truesize;
+	unsigned int new_truesize;
+	struct sk_buff *lp;
+
+	if (unlikely(p->len + len >= 65536 || NAPI_GRO_CB(skb)->flush))
+		return -E2BIG;
+
+	lp = NAPI_GRO_CB(p)->last;
+	pinfo = skb_shinfo(lp);
+
+	if (headlen <= offset) {
+		skb_frag_t *frag;
+		skb_frag_t *frag2;
+		int i = skbinfo->nr_frags;
+		int nr_frags = pinfo->nr_frags + i;
+
+		if (nr_frags > MAX_SKB_FRAGS)
+			goto merge;
+
+		offset -= headlen;
+		pinfo->nr_frags = nr_frags;
+		skbinfo->nr_frags = 0;
+
+		frag = pinfo->frags + nr_frags;
+		frag2 = skbinfo->frags + i;
+		do {
+			*--frag = *--frag2;
+		} while (--i);
+
+		skb_frag_off_add(frag, offset);
+		skb_frag_size_sub(frag, offset);
+
+		/* all fragments truesize : remove (head size + sk_buff) */
+		new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
+		delta_truesize = skb->truesize - new_truesize;
+
+		skb->truesize = new_truesize;
+		skb->len -= skb->data_len;
+		skb->data_len = 0;
+
+		NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE;
+		goto done;
+	} else if (skb->head_frag) {
+		int nr_frags = pinfo->nr_frags;
+		skb_frag_t *frag = pinfo->frags + nr_frags;
+		struct page *page = virt_to_head_page(skb->head);
+		unsigned int first_size = headlen - offset;
+		unsigned int first_offset;
+
+		if (nr_frags + 1 + skbinfo->nr_frags > MAX_SKB_FRAGS)
+			goto merge;
+
+		first_offset = skb->data -
+			       (unsigned char *)page_address(page) +
+			       offset;
+
+		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);
+
+		memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
+		/* We dont need to clear skbinfo->nr_frags here */
+
+		new_truesize = SKB_DATA_ALIGN(sizeof(struct sk_buff));
+		delta_truesize = skb->truesize - new_truesize;
+		skb->truesize = new_truesize;
+		NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
+		goto done;
+	}
+
+merge:
+	/* sk owenrship - if any - completely transferred to the aggregated packet */
+	skb->destructor = NULL;
+	delta_truesize = skb->truesize;
+	if (offset > headlen) {
+		unsigned int eat = offset - headlen;
+
+		skb_frag_off_add(&skbinfo->frags[0], eat);
+		skb_frag_size_sub(&skbinfo->frags[0], eat);
+		skb->data_len -= eat;
+		skb->len -= eat;
+		offset = headlen;
+	}
+
+	__skb_pull(skb, offset);
+
+	if (NAPI_GRO_CB(p)->last == p)
+		skb_shinfo(p)->frag_list = skb;
+	else
+		NAPI_GRO_CB(p)->last->next = skb;
+	NAPI_GRO_CB(p)->last = skb;
+	__skb_header_release(skb);
+	lp = p;
+
+done:
+	NAPI_GRO_CB(p)->count++;
+	p->data_len += len;
+	p->truesize += delta_truesize;
+	p->len += len;
+	if (lp != p) {
+		lp->data_len += len;
+		lp->truesize += delta_truesize;
+		lp->len += len;
+	}
+	NAPI_GRO_CB(skb)->same_flow = 1;
+	return 0;
+}