net: add skb_[inner_]tcp_all_headers helpers

Most drivers use "skb_transport_offset(skb) + tcp_hdrlen(skb)"
to compute headers length for a TCP packet, but others
use more convoluted (but equivalent) ways.

Add skb_tcp_all_headers() and skb_inner_tcp_all_headers()
helpers to harmonize this a bit.

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

1 files changed, 30 insertions, 0 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 1168302b7927..a9fbe22732c3 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -46,6 +46,36 @@ static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
 	return inner_tcp_hdr(skb)->doff * 4;
 }
 
+/**
+ * skb_tcp_all_headers - Returns size of all headers for a TCP packet
+ * @skb: buffer
+ *
+ * Used in TX path, for a packet known to be a TCP one.
+ *
+ * if (skb_is_gso(skb)) {
+ *         int hlen = skb_tcp_all_headers(skb);
+ *         ...
+ */
+static inline int skb_tcp_all_headers(const struct sk_buff *skb)
+{
+	return skb_transport_offset(skb) + tcp_hdrlen(skb);
+}
+
+/**
+ * skb_inner_tcp_all_headers - Returns size of all headers for an encap TCP packet
+ * @skb: buffer
+ *
+ * Used in TX path, for a packet known to be a TCP one.
+ *
+ * if (skb_is_gso(skb) && skb->encapsulation) {
+ *         int hlen = skb_inner_tcp_all_headers(skb);
+ *         ...
+ */
+static inline int skb_inner_tcp_all_headers(const struct sk_buff *skb)
+{
+	return skb_inner_transport_offset(skb) + inner_tcp_hdrlen(skb);
+}
+
 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
 {
 	return (tcp_hdr(skb)->doff - 5) * 4;