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Use power of 2 masking to make packet hash function fast.

    1: /*
    2:  * Copyright (c) 2003 Jeffrey Hsu
    3:  * All rights reserved.
    4:  *
    5:  * $DragonFly: src/sys/netinet/ip_demux.c,v 1.4 2004/03/05 19:47:28 hsu Exp $
    6:  */
    7: 
    8: #include "opt_inet.h"
    9: 
   10: #include <sys/param.h>
   11: #include <sys/systm.h>
   12: #include <sys/kernel.h>
   13: #include <sys/socket.h>
   14: #include <sys/socketvar.h>
   15: #include <sys/thread.h>
   16: #include <sys/sysctl.h>
   17: 
   18: #include <net/if.h>
   19: #include <net/netisr.h>
   20: 
   21: #include <netinet/in_systm.h>
   22: #include <netinet/in.h>
   23: #include <netinet/in_var.h>
   24: #include <netinet/in_pcb.h>
   25: #include <netinet/ip.h>
   26: #include <netinet/ip_var.h>
   27: #include <netinet/tcp.h>
   28: #include <netinet/tcpip.h>
   29: #include <netinet/tcp_var.h>
   30: #include <netinet/udp.h>
   31: #include <netinet/udp_var.h>
   32: 
   33: extern struct thread netisr_cpu[];
   34: 
   35: static struct thread tcp_thread[MAXCPU];
   36: static struct thread udp_thread[MAXCPU];
   37: 
   38: /*
   39:  * XXX when we remove the MP lock changes to this must be master-synchronized
   40:  */
   41: static int      ip_mthread_enable = 0;
   42: SYSCTL_INT(_net_inet_ip, OID_AUTO, mthread_enable, CTLFLAG_RW,
   43:     &ip_mthread_enable, 0, "");
   44: 
   45: static int
   46: INP_MPORT_HASH(in_addr_t src, in_addr_t dst, int sport, int dport)
   47: {
   48: 	/*
   49: 	 * Use low order bytes.
   50: 	 * This particular hash function is only good for ncpus < 256.
   51: 	 */
   52: #if (BYTE_ORDER == LITTLE_ENDIAN)
   53: 	return (((src >> 24) ^ (sport >> 8) ^ (dst >> 24) ^ (dport >> 8)) &
   54: 		ncpus2_mask);
   55: #else
   56: 	return ((src ^ sport ^ dst ^ dport) & ncpus2_mask);
   57: #endif
   58: }
   59: 
   60: lwkt_port_t
   61: ip_mport(struct mbuf *m)
   62: {
   63: 	struct ip *ip = mtod(m, struct ip *);
   64: 	int hlen;
   65: 	struct tcphdr *th;
   66: 	struct udphdr *uh;
   67: 	lwkt_port_t port;
   68: 
   69: 	if (ip_mthread_enable == 0)
   70: 		return (&netisr_cpu[0].td_msgport);
   71: 
   72: 	if (m->m_len < sizeof(struct ip) &&
   73: 	    (m = m_pullup(m, sizeof(struct ip))) == NULL) {
   74: 		ipstat.ips_toosmall++;
   75: 		return (NULL);
   76: 	}
   77: 
   78: 	/*
   79: 	 * XXX generic packet handling defrag on CPU 0 for now.
   80: 	 */
   81: 	if (ntohs(ip->ip_off) & (IP_MF | IP_OFFMASK))
   82: 		return (&netisr_cpu[0].td_msgport);
   83: 
   84: 	hlen = ip->ip_hl << 2;
   85: 
   86: 	switch (ip->ip_p) {
   87: 	case IPPROTO_TCP:
   88: 		if (m->m_len < sizeof(struct tcpiphdr) &&
   89: 		    (m = m_pullup(m, sizeof(struct tcpiphdr))) == NULL) {
   90: 			tcpstat.tcps_rcvshort++;
   91: 			return (NULL);
   92: 		}
   93: 
   94: 		th = (struct tcphdr *)((caddr_t)ip + hlen);
   95: 		port = &tcp_thread[INP_MPORT_HASH(ip->ip_src.s_addr,
   96: 		    ip->ip_dst.s_addr, th->th_sport, th->th_dport)].td_msgport;
   97: 		break;
   98: 	case IPPROTO_UDP:
   99: 		if (m->m_len < hlen + sizeof(struct udphdr) &&
  100: 		    (m = m_pullup(m, hlen + sizeof(struct udphdr))) == NULL) {
  101: 			udpstat.udps_hdrops++;
  102: 			return (NULL);
  103: 		}
  104: 
  105: 		uh = (struct udphdr *)((caddr_t)ip + hlen);
  106: 		port = &udp_thread[INP_MPORT_HASH(ip->ip_src.s_addr,
  107: 		    ip->ip_dst.s_addr, uh->uh_sport, uh->uh_dport)].td_msgport;
  108: 		break;
  109: 	default:
  110: 		port = &netisr_cpu[0].td_msgport;
  111: 		break;
  112: 	}
  113: 	KKASSERT(port->mp_putport != NULL);
  114: 
  115: 	return (port);
  116: }
  117: 
  118: lwkt_port_t
  119: tcp_soport(struct socket *so)
  120: {
  121: 	struct inpcb *inp = sotoinpcb(so);
  122: 
  123: 	return (&tcp_thread[INP_MPORT_HASH(inp->inp_laddr.s_addr,
  124: 	    inp->inp_faddr.s_addr, inp->inp_lport, inp->inp_fport)].td_msgport);
  125: }
  126: 
  127: lwkt_port_t
  128: udp_soport(struct socket *so)
  129: {
  130: 	struct inpcb *inp = sotoinpcb(so);
  131: 
  132: 	return (&udp_thread[INP_MPORT_HASH(inp->inp_laddr.s_addr,
  133: 	    inp->inp_faddr.s_addr, inp->inp_lport, inp->inp_fport)].td_msgport);
  134: }
  135: 
  136: void
  137: tcp_thread_init(void)
  138: {
  139: 	int cpu;
  140: 
  141: 	for (cpu = 0; cpu < ncpus2; cpu++) {
  142: 		lwkt_create(netmsg_service_loop, NULL, NULL, 
  143: 			&tcp_thread[cpu], 0, cpu, "tcp_thread %d", cpu);
  144: 	}
  145: }
  146: 
  147: void
  148: udp_thread_init(void)
  149: {
  150: 	int cpu;
  151: 
  152: 	for (cpu = 0; cpu < ncpus2; cpu++) {
  153: 		lwkt_create(netmsg_service_loop, NULL, NULL,
  154: 			&udp_thread[cpu], 0, cpu, "udp_thread %d", cpu);
  155: 	}
  156: }