[PATCH net] tcp: tracepoint: only call trace_tcp_send_reset with full socket

[Song Liu]

tracepoint tcp_send_reset requires a full socket to work. However, it
may be called when in TCP_TIME_WAIT:

        case TCP_TW_RST:
                tcp_v6_send_reset(sk, skb);
                inet_twsk_deschedule_put(inet_twsk(sk));
                goto discard_it;

To avoid this problem, this patch checks the socket with sk_fullsock()
before calling trace_tcp_send_reset().

Fixes: c24b14c46bb8 ("tcp: add tracepoint trace_tcp_send_reset")
Signed-off-by: Song Liu <songliubrav...@fb.com>
Reviewed-by: Lawrence Brakmo <bra...@fb.com>
---
 net/ipv4/tcp_ipv4.c | 3 ++-
 net/ipv6/tcp_ipv6.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 95738aa..f8ad397 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -705,7 +705,8 @@ static void tcp_v4_send_reset(const struct sock *sk, struct 
sk_buff *skb)
         */
        if (sk) {
                arg.bound_dev_if = sk->sk_bound_dev_if;
-               trace_tcp_send_reset(sk, skb);
+               if (sk_fullsock(sk))
+                       trace_tcp_send_reset(sk, skb);
        }
 
        BUILD_BUG_ON(offsetof(struct sock, sk_bound_dev_if) !=
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index a1ab29e..412139f 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -942,7 +942,8 @@ static void tcp_v6_send_reset(const struct sock *sk, struct 
sk_buff *skb)
 
        if (sk) {
                oif = sk->sk_bound_dev_if;
-               trace_tcp_send_reset(sk, skb);
+               if (sk_fullsock(sk))
+                       trace_tcp_send_reset(sk, skb);
        }
 
        tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, key, 1, 0, 0);
-- 
2.9.5