net: tcp_probe: kprobes: adapt jtcp_rcv_established signature

Daniel Borkmann · davem330 · commit d8cdeda6ddbc · 2013-08-22T16:19:50.000-07:00
This patches fixes a rather unproblematic function signature mismatch as the const specifier was missing for the th variable; and next to that it adds a build-time assertion so that future function signature mismatches for kprobes will not end badly, similarly as commit 2222299 ("net: sctp: add build check for sctp_sf_eat_sack_6_2/jsctp_sf_eat_sack") did it for SCTP. Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_probe.c b/net/ipv4/tcp_probe.c
@@ -92,7 +92,7 @@ static inline int tcp_probe_avail(void)
  * Note: arguments must match tcp_rcv_established()!
  */
 static int jtcp_rcv_established(struct sock *sk, struct sk_buff *skb,
-			       struct tcphdr *th, unsigned int len)
+				const struct tcphdr *th, unsigned int len)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
 	const struct inet_sock *inet = inet_sk(sk);
@@ -225,6 +225,13 @@ static __init int tcpprobe_init(void)
 {
 	int ret = -ENOMEM;
 
+	/* Warning: if the function signature of tcp_rcv_established,
+	 * has been changed, you also have to change the signature of
+	 * jtcp_rcv_established, otherwise you end up right here!
+	 */
+	BUILD_BUG_ON(__same_type(tcp_rcv_established,
+				 jtcp_rcv_established) == 0);
+
 	init_waitqueue_head(&tcp_probe.wait);
 	spin_lock_init(&tcp_probe.lock);
 
