net: hsr: save tx_flags and tag info of tagged skb

After a tag is created for an egress skb, the tag info and slave port
info is saved in the skb's shared info area so that the saved info can
be returned to user space application by upper core layer.

In this patch, only the support of saving HSR tag info of HSR PTP
over L2 skb is added.

Signed-off-by: WingMan Kwok <w-kwok2@ti.com>
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>

net/hsr/hsr_forward.c

@@ -31,6 +31,16 @@ struct hsr_frame_info {
 	bool is_from_san;
 };
 
+static inline int is_hsr_l2ptp(struct sk_buff *skb)
+{
+	struct hsr_ethhdr *hsr_ethhdr;
+
+	hsr_ethhdr = (struct hsr_ethhdr *)skb_mac_header(skb);
+
+	return (hsr_ethhdr->ethhdr.h_proto == htons(ETH_P_HSR) &&
+		hsr_ethhdr->hsr_tag.encap_proto == htons(ETH_P_1588));
+}
+
 /* The uses I can see for these HSR supervision frames are:
  * 1) Use the frames that are sent after node initialization ("HSR_TLV.Type =
  *    22") to reset any sequence_nr counters belonging to that node. Useful if
@@ -289,6 +299,9 @@ static struct sk_buff *create_tagged_skb(struct sk_buff *skb_o,
 	int movelen;
 	unsigned char *dst, *src;
 	struct sk_buff *skb;
+	struct skb_redundant_info *sred;
+	struct hsr_ethhdr *hsr_ethhdr;
+	u16 s;
 
 	if (port->hsr->prot_version > HSR_V1) {
 		skb = skb_copy_expand(skb_o, skb_headroom(skb_o),
@@ -321,6 +334,22 @@ static struct sk_buff *create_tagged_skb(struct sk_buff *skb_o,
 
 	hsr_fill_tag(skb, frame, port, port->hsr->prot_version);
 
+	skb_shinfo(skb)->tx_flags = skb_shinfo(skb_o)->tx_flags;
+	skb->sk = skb_o->sk;
+
+	/* TODO: should check socket option instead? */
+	if (is_hsr_l2ptp(skb)) {
+		sred = skb_redinfo(skb);
+		/* assumes no vlan */
+		hsr_ethhdr = (struct hsr_ethhdr *)skb_mac_header(skb);
+		sred->io_port = port->type;
+		sred->ethertype = ntohs(hsr_ethhdr->ethhdr.h_proto);
+		s = ntohs(hsr_ethhdr->hsr_tag.path_and_LSDU_size);
+		sred->lsdu_size = s & 0xfff;
+		sred->pathid = (s >> 12) & 0xf;
+		sred->seqnr = hsr_get_skb_sequence_nr(skb);
+	}
+
 	return skb;
 }