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that if we sort the incoming SACK blocks, we can update the scoreboard in one pass of the scoreboard. The added overhead of sorting upto 4 sack blocks is much lower than traversing (potentially) large scoreboards multiple times. The code was updating the scoreboard with multiple passes over it (once for each sack option). The rewrite fixes that, reducing the complexity of the main loop from O(n^2) to O(n). Submitted by: Mohan Srinivasan, Noritoshi Demizu. Reviewed by: Raja Mukerji.
714 lines
22 KiB
C
714 lines
22 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
|
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)tcp_sack.c 8.12 (Berkeley) 5/24/95
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* $FreeBSD$
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*/
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/*-
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
|
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* modification, are permitted provided that the following conditions
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* are met:
|
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* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
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* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
|
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @@(#)COPYRIGHT 1.1 (NRL) 17 January 1995
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*
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* NRL grants permission for redistribution and use in source and binary
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* forms, with or without modification, of the software and documentation
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* created at NRL provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgements:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* This product includes software developed at the Information
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* Technology Division, US Naval Research Laboratory.
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* 4. Neither the name of the NRL nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS
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* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* The views and conclusions contained in the software and documentation
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* are those of the authors and should not be interpreted as representing
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* official policies, either expressed or implied, of the US Naval
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* Research Laboratory (NRL).
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*/
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#include "opt_inet.h"
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#include "opt_inet6.h"
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#include "opt_ipsec.h"
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#include "opt_tcpdebug.h"
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#include "opt_tcp_input.h"
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#include "opt_tcp_sack.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/proc.h> /* for proc0 declaration */
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#include <sys/protosw.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/syslog.h>
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#include <sys/systm.h>
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#include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */
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#include <vm/uma.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/ip_icmp.h> /* for ICMP_BANDLIM */
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#include <netinet/in_var.h>
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#include <netinet/icmp_var.h> /* for ICMP_BANDLIM */
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#include <netinet/in_pcb.h>
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#include <netinet/ip_var.h>
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#include <netinet/ip6.h>
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#include <netinet/icmp6.h>
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#include <netinet6/nd6.h>
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#include <netinet6/ip6_var.h>
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#include <netinet6/in6_pcb.h>
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#include <netinet/tcp.h>
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#include <netinet/tcp_fsm.h>
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#include <netinet/tcp_seq.h>
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#include <netinet/tcp_timer.h>
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#include <netinet/tcp_var.h>
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#include <netinet6/tcp6_var.h>
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#include <netinet/tcpip.h>
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#ifdef TCPDEBUG
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#include <netinet/tcp_debug.h>
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#endif /* TCPDEBUG */
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#ifdef FAST_IPSEC
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#include <netipsec/ipsec.h>
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#include <netipsec/ipsec6.h>
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#endif
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#ifdef IPSEC
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#include <netinet6/ipsec.h>
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#include <netinet6/ipsec6.h>
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#include <netkey/key.h>
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#endif /*IPSEC*/
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#include <machine/in_cksum.h>
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extern struct uma_zone *sack_hole_zone;
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SYSCTL_NODE(_net_inet_tcp, OID_AUTO, sack, CTLFLAG_RW, 0, "TCP SACK");
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int tcp_do_sack = 1;
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SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, enable, CTLFLAG_RW,
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&tcp_do_sack, 0, "Enable/Disable TCP SACK support");
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TUNABLE_INT("net.inet.tcp.sack.enable", &tcp_do_sack);
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static int tcp_sack_maxholes = 128;
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SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, maxholes, CTLFLAG_RW,
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&tcp_sack_maxholes, 0,
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"Maximum number of TCP SACK holes allowed per connection");
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static int tcp_sack_globalmaxholes = 65536;
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SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, globalmaxholes, CTLFLAG_RW,
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&tcp_sack_globalmaxholes, 0,
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"Global maximum number of TCP SACK holes");
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static int tcp_sack_globalholes = 0;
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SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, globalholes, CTLFLAG_RD,
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&tcp_sack_globalholes, 0,
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"Global number of TCP SACK holes currently allocated");
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/*
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* This function is called upon receipt of new valid data (while not in header
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* prediction mode), and it updates the ordered list of sacks.
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*/
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void
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tcp_update_sack_list(struct tcpcb *tp, tcp_seq rcv_start, tcp_seq rcv_end)
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{
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/*
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* First reported block MUST be the most recent one. Subsequent
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* blocks SHOULD be in the order in which they arrived at the
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* receiver. These two conditions make the implementation fully
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* compliant with RFC 2018.
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*/
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struct sackblk head_blk, saved_blks[MAX_SACK_BLKS];
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int num_head, num_saved, i;
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INP_LOCK_ASSERT(tp->t_inpcb);
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/* Check arguments */
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KASSERT(SEQ_LT(rcv_start, rcv_end), ("rcv_start < rcv_end"));
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/* SACK block for the received segment. */
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head_blk.start = rcv_start;
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head_blk.end = rcv_end;
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/*
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* Merge updated SACK blocks into head_blk, and
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* save unchanged SACK blocks into saved_blks[].
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* num_saved will have the number of the saved SACK blocks.
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*/
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num_saved = 0;
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for (i = 0; i < tp->rcv_numsacks; i++) {
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tcp_seq start = tp->sackblks[i].start;
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tcp_seq end = tp->sackblks[i].end;
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if (SEQ_GEQ(start, end) || SEQ_LEQ(start, tp->rcv_nxt)) {
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/*
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* Discard this SACK block.
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*/
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} else if (SEQ_LEQ(head_blk.start, end) &&
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SEQ_GEQ(head_blk.end, start)) {
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/*
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* Merge this SACK block into head_blk.
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* This SACK block itself will be discarded.
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*/
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if (SEQ_GT(head_blk.start, start))
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head_blk.start = start;
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if (SEQ_LT(head_blk.end, end))
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head_blk.end = end;
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} else {
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/*
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* Save this SACK block.
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*/
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saved_blks[num_saved].start = start;
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saved_blks[num_saved].end = end;
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num_saved++;
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}
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}
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/*
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* Update SACK list in tp->sackblks[].
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*/
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num_head = 0;
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if (SEQ_GT(head_blk.start, tp->rcv_nxt)) {
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/*
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* The received data segment is an out-of-order segment.
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* Put head_blk at the top of SACK list.
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*/
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tp->sackblks[0] = head_blk;
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num_head = 1;
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/*
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* If the number of saved SACK blocks exceeds its limit,
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* discard the last SACK block.
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*/
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if (num_saved >= MAX_SACK_BLKS)
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num_saved--;
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}
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if (num_saved > 0) {
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/*
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* Copy the saved SACK blocks back.
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*/
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bcopy(saved_blks, &tp->sackblks[num_head],
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sizeof(struct sackblk) * num_saved);
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}
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/* Save the number of SACK blocks. */
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tp->rcv_numsacks = num_head + num_saved;
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}
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/*
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* Delete all receiver-side SACK information.
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*/
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void
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tcp_clean_sackreport(tp)
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struct tcpcb *tp;
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{
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int i;
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INP_LOCK_ASSERT(tp->t_inpcb);
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tp->rcv_numsacks = 0;
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for (i = 0; i < MAX_SACK_BLKS; i++)
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tp->sackblks[i].start = tp->sackblks[i].end=0;
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}
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/*
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* Allocate struct sackhole.
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*/
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static struct sackhole *
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tcp_sackhole_alloc(struct tcpcb *tp, tcp_seq start, tcp_seq end)
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{
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struct sackhole *hole;
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if (tp->snd_numholes >= tcp_sack_maxholes ||
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tcp_sack_globalholes >= tcp_sack_globalmaxholes) {
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tcpstat.tcps_sack_sboverflow++;
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return NULL;
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}
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hole = (struct sackhole *)uma_zalloc(sack_hole_zone, M_NOWAIT);
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if (hole == NULL)
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return NULL;
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hole->start = start;
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hole->end = end;
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hole->rxmit = start;
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tp->snd_numholes++;
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tcp_sack_globalholes++;
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return hole;
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}
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/*
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* Free struct sackhole.
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*/
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static void
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tcp_sackhole_free(struct tcpcb *tp, struct sackhole *hole)
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{
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uma_zfree(sack_hole_zone, hole);
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tp->snd_numholes--;
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tcp_sack_globalholes--;
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KASSERT(tp->snd_numholes >= 0, ("tp->snd_numholes >= 0"));
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KASSERT(tcp_sack_globalholes >= 0, ("tcp_sack_globalholes >= 0"));
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}
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/*
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* Process the TCP SACK option. Returns 1 if tcp_dooptions() should continue,
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* and 0 otherwise, if the option was fine. tp->snd_holes is an ordered list
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* of holes (oldest to newest, in terms of the sequence space).
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*/
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int
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tcp_sack_option(struct tcpcb *tp, struct tcphdr *th, u_char *cp, int optlen)
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{
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int tmp_olen;
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u_char *tmp_cp;
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struct sackhole *cur, *temp;
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struct sackblk sack, sack_blocks[TCP_MAX_SACK];
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int i, j, next_sack_blk, num_sack_blks;
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INP_LOCK_ASSERT(tp->t_inpcb);
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if (!tp->sack_enable)
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return (1);
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if ((th->th_flags & TH_ACK) == 0)
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return (1);
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/* Note: TCPOLEN_SACK must be 2*sizeof(tcp_seq) */
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if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0)
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return (1);
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/* If ack is outside [snd_una, snd_max], ignore the SACK options */
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if (SEQ_LT(th->th_ack, tp->snd_una) || SEQ_GT(th->th_ack, tp->snd_max))
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return (1);
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tmp_cp = cp + 2;
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tmp_olen = optlen - 2;
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tcpstat.tcps_sack_rcv_blocks++;
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/*
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* Sort the SACK blocks so we can update the scoreboard
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* with just one pass. The overhead of sorting upto 4 elements
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* is less than making 3 passes over the scoreboard.
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*/
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num_sack_blks = 0;
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while (tmp_olen > 0) {
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bcopy(tmp_cp, &sack, sizeof(sack));
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sack.start = ntohl(sack.start);
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sack.end = ntohl(sack.end);
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if (SEQ_GT(sack.end, sack.start) &&
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SEQ_GT(sack.start, tp->snd_una) &&
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SEQ_GT(sack.start, th->th_ack) &&
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SEQ_LEQ(sack.end, tp->snd_max))
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sack_blocks[num_sack_blks++] = sack;
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tmp_olen -= TCPOLEN_SACK;
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tmp_cp += TCPOLEN_SACK;
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}
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if (num_sack_blks == 0)
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return 0;
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/* Bubble sort */
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for (i = 0; i < num_sack_blks; i++) {
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for (j = i + 1; j < num_sack_blks; j++) {
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if (SEQ_GT(sack_blocks[i].start,
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sack_blocks[j].start)){
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sack = sack_blocks[i];
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sack_blocks[i] = sack_blocks[j];
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sack_blocks[j] = sack;
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}
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}
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}
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if (TAILQ_EMPTY(&tp->snd_holes))
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/*
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* Empty scoreboard. Need to initialize rcv_lastsack (it may be
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* uninitialized or have a bogus value). Scoreboard holes
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* (from the sack blocks received) are created later below (in
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* the logic that adds holes to the tail of the scoreboard).
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*/
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tp->rcv_lastsack = tp->snd_una;
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next_sack_blk = 0;
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cur = TAILQ_FIRST(&tp->snd_holes);
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/*
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* Since the incoming sack blocks are sorted, we can process them
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* making one sweep of the scoreboard.
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*/
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while ((next_sack_blk < num_sack_blks) && (cur != NULL)) {
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sack = sack_blocks[next_sack_blk];
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if (SEQ_LT(tp->rcv_lastsack, sack.start))
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/*
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* The sack block acks data to the right of all the holes
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* in the scoreboard. No need to iterate over the
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* scoreboard anymore.
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*/
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break;
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if (SEQ_LEQ(sack.end, cur->start)) {
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/*
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* SACKs data before the current hole.
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* Ignore the sack block. Go to the next sack
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* block.
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*/
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next_sack_blk++;
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continue;
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}
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if (SEQ_GEQ(sack.start, cur->end)) {
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/*
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* SACKs data beyond the current hole.
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* Go to the next hole.
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*/
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cur = TAILQ_NEXT(cur, scblink);
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continue;
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}
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tp->sackhint.sack_bytes_rexmit -= (cur->rxmit - cur->start);
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KASSERT(tp->sackhint.sack_bytes_rexmit >= 0,
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("sackhint bytes rtx >= 0"));
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if (SEQ_LEQ(sack.start, cur->start)) {
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/* Data acks at least the beginning of hole */
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if (SEQ_GEQ(sack.end, cur->end)) {
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/* Acks entire hole, so delete hole */
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if (tp->sackhint.nexthole == cur)
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tp->sackhint.nexthole =
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TAILQ_NEXT(cur, scblink);
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temp = cur;
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cur = TAILQ_NEXT(cur, scblink);
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TAILQ_REMOVE(&tp->snd_holes, temp, scblink);
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tcp_sackhole_free(tp, temp);
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/*
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* The sack block may ack all or part of the next
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* hole too, so continue onto the next hole.
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*/
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continue;
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} else {
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/* Move start of hole forward */
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cur->start = sack.end;
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cur->rxmit = SEQ_MAX(cur->rxmit, cur->start);
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}
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} else {
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if (SEQ_GEQ(sack.end, cur->end)) {
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/* Move end of hole backward */
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cur->end = sack.start;
|
|
cur->rxmit = SEQ_MIN(cur->rxmit, cur->end);
|
|
} else {
|
|
/*
|
|
* ACKs some data in middle of a hole; need to
|
|
* split current hole
|
|
*/
|
|
temp = tcp_sackhole_alloc(tp, sack.end,
|
|
cur->end);
|
|
if (temp != NULL) {
|
|
if (SEQ_GT(cur->rxmit, temp->rxmit))
|
|
temp->rxmit = cur->rxmit;
|
|
TAILQ_INSERT_AFTER(&tp->snd_holes,
|
|
cur, temp, scblink);
|
|
cur->end = sack.start;
|
|
cur->rxmit = SEQ_MIN(cur->rxmit, cur->end);
|
|
tp->sackhint.sack_bytes_rexmit +=
|
|
(cur->rxmit - cur->start);
|
|
cur = temp;
|
|
}
|
|
}
|
|
}
|
|
tp->sackhint.sack_bytes_rexmit += (cur->rxmit - cur->start);
|
|
/*
|
|
* Testing sack.end against cur->end tells us whether we're done
|
|
* with the sack block or the sack hole. Accordingly, we advance
|
|
* one or the other.
|
|
*/
|
|
if (SEQ_GEQ(sack.end, cur->end))
|
|
cur = TAILQ_NEXT(cur, scblink);
|
|
else
|
|
next_sack_blk++;
|
|
}
|
|
/* Iterated all the holes in the scoreboard. Add new holes. */
|
|
for ( ; next_sack_blk < num_sack_blks ; next_sack_blk++) {
|
|
sack = sack_blocks[next_sack_blk];
|
|
/*
|
|
* The two SEQ_LT() checks here that test rcv_laststart against
|
|
* sack.start and sack.end seem redundant, but they're necessary
|
|
* to deal with overlapping sack blocks.
|
|
*/
|
|
if (SEQ_LT(tp->rcv_lastsack, sack.start)) {
|
|
/* Need to append new hole at end. */
|
|
temp = tcp_sackhole_alloc(tp, tp->rcv_lastsack,
|
|
sack.start);
|
|
if (temp == NULL)
|
|
continue; /* ENOBUFS */
|
|
TAILQ_INSERT_TAIL(&tp->snd_holes, temp, scblink);
|
|
tp->rcv_lastsack = sack.end;
|
|
if (tp->sackhint.nexthole == NULL)
|
|
tp->sackhint.nexthole = temp;
|
|
}
|
|
if (SEQ_LT(tp->rcv_lastsack, sack.end))
|
|
tp->rcv_lastsack = sack.end;
|
|
}
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Delete stale (i.e, cumulatively ack'd) holes. Hole is deleted only if
|
|
* it is completely acked; otherwise, tcp_sack_option(), called from
|
|
* tcp_dooptions(), will fix up the hole.
|
|
*/
|
|
void
|
|
tcp_del_sackholes(tp, th)
|
|
struct tcpcb *tp;
|
|
struct tcphdr *th;
|
|
{
|
|
INP_LOCK_ASSERT(tp->t_inpcb);
|
|
if (tp->sack_enable && tp->t_state != TCPS_LISTEN) {
|
|
/* max because this could be an older ack just arrived */
|
|
tcp_seq lastack = SEQ_GT(th->th_ack, tp->snd_una) ?
|
|
th->th_ack : tp->snd_una;
|
|
struct sackhole *cur = TAILQ_FIRST(&tp->snd_holes);
|
|
struct sackhole *prev;
|
|
while (cur)
|
|
if (SEQ_LEQ(cur->end, lastack)) {
|
|
prev = cur;
|
|
tp->sackhint.sack_bytes_rexmit -=
|
|
(cur->rxmit - cur->start);
|
|
if (tp->sackhint.nexthole == cur)
|
|
tp->sackhint.nexthole =
|
|
TAILQ_NEXT(cur, scblink);
|
|
cur = TAILQ_NEXT(cur, scblink);
|
|
TAILQ_REMOVE(&tp->snd_holes, prev, scblink);
|
|
tcp_sackhole_free(tp, prev);
|
|
} else if (SEQ_LT(cur->start, lastack)) {
|
|
if (SEQ_LT(cur->rxmit, lastack)) {
|
|
tp->sackhint.sack_bytes_rexmit -=
|
|
(cur->rxmit - cur->start);
|
|
cur->rxmit = lastack;
|
|
} else
|
|
tp->sackhint.sack_bytes_rexmit -=
|
|
(lastack - cur->start);
|
|
cur->start = lastack;
|
|
break;
|
|
} else
|
|
break;
|
|
}
|
|
}
|
|
|
|
void
|
|
tcp_free_sackholes(struct tcpcb *tp)
|
|
{
|
|
struct sackhole *q;
|
|
|
|
INP_LOCK_ASSERT(tp->t_inpcb);
|
|
while ((q = TAILQ_FIRST(&tp->snd_holes)) != NULL) {
|
|
TAILQ_REMOVE(&tp->snd_holes, q, scblink);
|
|
tcp_sackhole_free(tp, q);
|
|
}
|
|
tp->sackhint.nexthole = NULL;
|
|
tp->sackhint.sack_bytes_rexmit = 0;
|
|
|
|
KASSERT(tp->snd_numholes == 0, ("tp->snd_numholes == 0"));
|
|
}
|
|
|
|
/*
|
|
* Partial ack handling within a sack recovery episode.
|
|
* Keeping this very simple for now. When a partial ack
|
|
* is received, force snd_cwnd to a value that will allow
|
|
* the sender to transmit no more than 2 segments.
|
|
* If necessary, a better scheme can be adopted at a
|
|
* later point, but for now, the goal is to prevent the
|
|
* sender from bursting a large amount of data in the midst
|
|
* of sack recovery.
|
|
*/
|
|
void
|
|
tcp_sack_partialack(tp, th)
|
|
struct tcpcb *tp;
|
|
struct tcphdr *th;
|
|
{
|
|
int num_segs = 1;
|
|
|
|
INP_LOCK_ASSERT(tp->t_inpcb);
|
|
callout_stop(tp->tt_rexmt);
|
|
tp->t_rtttime = 0;
|
|
/* send one or 2 segments based on how much new data was acked */
|
|
if (((th->th_ack - tp->snd_una) / tp->t_maxseg) > 2)
|
|
num_segs = 2;
|
|
tp->snd_cwnd = (tp->sackhint.sack_bytes_rexmit +
|
|
(tp->snd_nxt - tp->sack_newdata) +
|
|
num_segs * tp->t_maxseg);
|
|
if (tp->snd_cwnd > tp->snd_ssthresh)
|
|
tp->snd_cwnd = tp->snd_ssthresh;
|
|
tp->t_flags |= TF_ACKNOW;
|
|
(void) tcp_output(tp);
|
|
}
|
|
|
|
/*
|
|
* Debug version of tcp_sack_output() that walks the scoreboard. Used for
|
|
* now to sanity check the hint.
|
|
*/
|
|
static struct sackhole *
|
|
tcp_sack_output_debug(struct tcpcb *tp, int *sack_bytes_rexmt)
|
|
{
|
|
struct sackhole *p;
|
|
|
|
INP_LOCK_ASSERT(tp->t_inpcb);
|
|
*sack_bytes_rexmt = 0;
|
|
TAILQ_FOREACH(p, &tp->snd_holes, scblink) {
|
|
if (SEQ_LT(p->rxmit, p->end)) {
|
|
if (SEQ_LT(p->rxmit, tp->snd_una)) {/* old SACK hole */
|
|
continue;
|
|
}
|
|
*sack_bytes_rexmt += (p->rxmit - p->start);
|
|
break;
|
|
}
|
|
*sack_bytes_rexmt += (p->rxmit - p->start);
|
|
}
|
|
return (p);
|
|
}
|
|
|
|
/*
|
|
* Returns the next hole to retransmit and the number of retransmitted bytes
|
|
* from the scoreboard. We store both the next hole and the number of
|
|
* retransmitted bytes as hints (and recompute these on the fly upon SACK/ACK
|
|
* reception). This avoids scoreboard traversals completely.
|
|
*
|
|
* The loop here will traverse *at most* one link. Here's the argument.
|
|
* For the loop to traverse more than 1 link before finding the next hole to
|
|
* retransmit, we would need to have at least 1 node following the current hint
|
|
* with (rxmit == end). But, for all holes following the current hint,
|
|
* (start == rxmit), since we have not yet retransmitted from them. Therefore,
|
|
* in order to traverse more 1 link in the loop below, we need to have at least
|
|
* one node following the current hint with (start == rxmit == end).
|
|
* But that can't happen, (start == end) means that all the data in that hole
|
|
* has been sacked, in which case, the hole would have been removed from the
|
|
* scoreboard.
|
|
*/
|
|
struct sackhole *
|
|
tcp_sack_output(struct tcpcb *tp, int *sack_bytes_rexmt)
|
|
{
|
|
struct sackhole *hole = NULL, *dbg_hole = NULL;
|
|
int dbg_bytes_rexmt;
|
|
|
|
INP_LOCK_ASSERT(tp->t_inpcb);
|
|
dbg_hole = tcp_sack_output_debug(tp, &dbg_bytes_rexmt);
|
|
*sack_bytes_rexmt = tp->sackhint.sack_bytes_rexmit;
|
|
hole = tp->sackhint.nexthole;
|
|
if (hole == NULL || SEQ_LT(hole->rxmit, hole->end))
|
|
goto out;
|
|
while ((hole = TAILQ_NEXT(hole, scblink)) != NULL) {
|
|
if (SEQ_LT(hole->rxmit, hole->end)) {
|
|
tp->sackhint.nexthole = hole;
|
|
break;
|
|
}
|
|
}
|
|
out:
|
|
if (dbg_hole != hole) {
|
|
printf("%s: Computed sack hole not the same as cached value\n", __func__);
|
|
hole = dbg_hole;
|
|
}
|
|
if (*sack_bytes_rexmt != dbg_bytes_rexmt) {
|
|
printf("%s: Computed sack_bytes_retransmitted (%d) not"
|
|
"the same as cached value (%d)\n",
|
|
__func__, dbg_bytes_rexmt, *sack_bytes_rexmt);
|
|
*sack_bytes_rexmt = dbg_bytes_rexmt;
|
|
}
|
|
return (hole);
|
|
}
|
|
|
|
/*
|
|
* After a timeout, the SACK list may be rebuilt. This SACK information
|
|
* should be used to avoid retransmitting SACKed data. This function
|
|
* traverses the SACK list to see if snd_nxt should be moved forward.
|
|
*/
|
|
void
|
|
tcp_sack_adjust(struct tcpcb *tp)
|
|
{
|
|
struct sackhole *p, *cur = TAILQ_FIRST(&tp->snd_holes);
|
|
|
|
INP_LOCK_ASSERT(tp->t_inpcb);
|
|
if (cur == NULL)
|
|
return; /* No holes */
|
|
if (SEQ_GEQ(tp->snd_nxt, tp->rcv_lastsack))
|
|
return; /* We're already beyond any SACKed blocks */
|
|
/*
|
|
* Two cases for which we want to advance snd_nxt:
|
|
* i) snd_nxt lies between end of one hole and beginning of another
|
|
* ii) snd_nxt lies between end of last hole and rcv_lastsack
|
|
*/
|
|
while ((p = TAILQ_NEXT(cur, scblink)) != NULL) {
|
|
if (SEQ_LT(tp->snd_nxt, cur->end))
|
|
return;
|
|
if (SEQ_GEQ(tp->snd_nxt, p->start))
|
|
cur = p;
|
|
else {
|
|
tp->snd_nxt = p->start;
|
|
return;
|
|
}
|
|
}
|
|
if (SEQ_LT(tp->snd_nxt, cur->end))
|
|
return;
|
|
tp->snd_nxt = tp->rcv_lastsack;
|
|
return;
|
|
}
|