tcp: fix compile error if !CONFIG_SYSCTL

tcp_tx_skb_cache_key and tcp_rx_skb_cache_key must be available
even if CONFIG_SYSCTL is not set.

Fixes: 0b7d7f6b ("tcp: add tcp_tx_skb_cache sysctl")
Fixes: ede61ca4 ("tcp: add tcp_rx_skb_cache sysctl")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/sysctl_net_ipv4.c

@@ -51,11 +51,6 @@ static int comp_sack_nr_max = 255;
 static u32 u32_max_div_HZ = UINT_MAX / HZ;
 static int one_day_secs = 24 * 3600;
 
-DEFINE_STATIC_KEY_FALSE(tcp_rx_skb_cache_key);
-EXPORT_SYMBOL(tcp_rx_skb_cache_key);
-
-DEFINE_STATIC_KEY_FALSE(tcp_tx_skb_cache_key);
-
 /* obsolete */
 static int sysctl_tcp_low_latency __read_mostly;
 

net/ipv4/tcp.c

@@ -317,6 +317,11 @@ struct tcp_splice_state {
 unsigned long tcp_memory_pressure __read_mostly;
 EXPORT_SYMBOL_GPL(tcp_memory_pressure);
 
+DEFINE_STATIC_KEY_FALSE(tcp_rx_skb_cache_key);
+EXPORT_SYMBOL(tcp_rx_skb_cache_key);
+
+DEFINE_STATIC_KEY_FALSE(tcp_tx_skb_cache_key);
+
 void tcp_enter_memory_pressure(struct sock *sk)
 {
 	unsigned long val;