[PATCH net-next 01/19] net: tcp: introduce tcp_drop_reason()

[menglong8 . dong]

From: Menglong Dong <imagedong@xxxxxxxxxxx>

For TCP protocol, tcp_drop() is used to free the skb when it needs
to be dropped. To make use of kfree_skb_reason() and collect drop
reasons, introduce the function tcp_drop_reason().

tcp_drop_reason() will finally call kfree_skb_reason() and pass the
drop reason to 'kfree_skb' tracepoint.

PS: __kfree_skb() was used in tcp_drop(), I'm not sure if it's ok
to replace it with kfree_skb_reason().

Signed-off-by: Menglong Dong <imagedong@xxxxxxxxxxx>
---
 net/ipv4/tcp_input.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index af94a6d22a9d..e3811afd1756 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4684,10 +4684,19 @@ static bool tcp_ooo_try_coalesce(struct sock *sk,
 	return res;
 }
 
-static void tcp_drop(struct sock *sk, struct sk_buff *skb)
+static void tcp_drop_reason(struct sock *sk, struct sk_buff *skb,
+			    enum skb_drop_reason reason)
 {
 	sk_drops_add(sk, skb);
-	__kfree_skb(skb);
+	/* why __kfree_skb() used here before, other than kfree_skb()?
+	 * confusing......
+	 */
+	kfree_skb_reason(skb, reason);
+}
+
+static inline void tcp_drop(struct sock *sk, struct sk_buff *skb)
+{
+	tcp_drop_reason(sk, skb, SKB_DROP_REASON_NOT_SPECIFIED);
 }
 
 /* This one checks to see if we can put data from the
-- 
2.34.1