[TCP]: Use BUILD_BUG_ON for tcp_skb_cb size checking

The sizeof(struct tcp_skb_cb) should not be less than the
sizeof(skb->cb). This is checked in net/ipv4/tcp.c, but
this check can be made more gracefully.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index eb77088f3054a9207aa4559ca311e3f3a879b379..fdaf965a67948fbc354e4db2ba4e3a2d69a68e21 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2563,7 +2563,6 @@ void tcp_done(struct sock *sk)
 }
 EXPORT_SYMBOL_GPL(tcp_done);
 
-extern void __skb_cb_too_small_for_tcp(int, int);
 extern struct tcp_congestion_ops tcp_reno;
 
 static __initdata unsigned long thash_entries;
@@ -2582,9 +2581,7 @@ void __init tcp_init(void)
        unsigned long limit;
        int order, i, max_share;
 
-       if (sizeof(struct tcp_skb_cb) > sizeof(skb->cb))
-               __skb_cb_too_small_for_tcp(sizeof(struct tcp_skb_cb),
-                                          sizeof(skb->cb));
+       BUILD_BUG_ON(sizeof(struct tcp_skb_cb) > sizeof(skb->cb));
 
        tcp_hashinfo.bind_bucket_cachep =
                kmem_cache_create("tcp_bind_bucket",