LINUX_MIB_TCPSPURIOUSRTOS,              /* TCPSpuriousRTOs */
        LINUX_MIB_TCPMD5NOTFOUND,               /* TCPMD5NotFound */
        LINUX_MIB_TCPMD5UNEXPECTED,             /* TCPMD5Unexpected */
+       LINUX_MIB_SACKSHIFTED,
+       LINUX_MIB_SACKMERGED,
+       LINUX_MIB_SACKSHIFTFALLBACK,
        __LINUX_MIB_MAX
 };
 
 
        SNMP_MIB_ITEM("TCPSpuriousRTOs", LINUX_MIB_TCPSPURIOUSRTOS),
        SNMP_MIB_ITEM("TCPMD5NotFound", LINUX_MIB_TCPMD5NOTFOUND),
        SNMP_MIB_ITEM("TCPMD5Unexpected", LINUX_MIB_TCPMD5UNEXPECTED),
+       SNMP_MIB_ITEM("TCPSackShifted", LINUX_MIB_SACKSHIFTED),
+       SNMP_MIB_ITEM("TCPSackMerged", LINUX_MIB_SACKMERGED),
+       SNMP_MIB_ITEM("TCPSackShiftFallback", LINUX_MIB_SACKSHIFTFALLBACK),
        SNMP_MIB_SENTINEL
 };
 
 
 
        if (skb->len > 0) {
                BUG_ON(!tcp_skb_pcount(skb));
+               NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKSHIFTED);
                return 0;
        }
 
        tcp_unlink_write_queue(skb, sk);
        sk_wmem_free_skb(sk, skb);
 
+       NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKMERGED);
+
        return 1;
 }
 
        return skb;
 
 fallback:
+       NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SACKSHIFTFALLBACK);
        return NULL;
 }