1714e18e79
(tcp_sack_output_debug checks cached hints aginst computed values by walking the scoreboard and reports discrepancies). The sack hinting code has been stable for many months now so it is time for the debug code to go. Leaving tcp_sack_output_debug ifdef'ed out in case we need to resurrect it at a later point.
705 lines
22 KiB
C
705 lines
22 KiB
C
/*-
|
|
* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
|
|
* The Regents of the University of California. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 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
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 4. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* @(#)tcp_sack.c 8.12 (Berkeley) 5/24/95
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
/*-
|
|
* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994
|
|
* The Regents of the University of California. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 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
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* @@(#)COPYRIGHT 1.1 (NRL) 17 January 1995
|
|
*
|
|
* NRL grants permission for redistribution and use in source and binary
|
|
* forms, with or without modification, of the software and documentation
|
|
* created at NRL provided that the following conditions are met:
|
|
*
|
|
* 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
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgements:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* This product includes software developed at the Information
|
|
* Technology Division, US Naval Research Laboratory.
|
|
* 4. Neither the name of the NRL nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS
|
|
* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
|
|
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR
|
|
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
|
|
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
|
|
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
|
|
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
|
|
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
|
|
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
|
|
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
* The views and conclusions contained in the software and documentation
|
|
* are those of the authors and should not be interpreted as representing
|
|
* official policies, either expressed or implied, of the US Naval
|
|
* Research Laboratory (NRL).
|
|
*/
|
|
#include "opt_inet.h"
|
|
#include "opt_inet6.h"
|
|
#include "opt_tcpdebug.h"
|
|
#include "opt_tcp_input.h"
|
|
#include "opt_tcp_sack.h"
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/sysctl.h>
|
|
#include <sys/malloc.h>
|
|
#include <sys/mbuf.h>
|
|
#include <sys/proc.h> /* for proc0 declaration */
|
|
#include <sys/protosw.h>
|
|
#include <sys/socket.h>
|
|
#include <sys/socketvar.h>
|
|
#include <sys/syslog.h>
|
|
#include <sys/systm.h>
|
|
|
|
#include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */
|
|
|
|
#include <vm/uma.h>
|
|
|
|
#include <net/if.h>
|
|
#include <net/route.h>
|
|
|
|
#include <netinet/in.h>
|
|
#include <netinet/in_systm.h>
|
|
#include <netinet/ip.h>
|
|
#include <netinet/in_var.h>
|
|
#include <netinet/in_pcb.h>
|
|
#include <netinet/ip_var.h>
|
|
#include <netinet/ip6.h>
|
|
#include <netinet/icmp6.h>
|
|
#include <netinet6/nd6.h>
|
|
#include <netinet6/ip6_var.h>
|
|
#include <netinet6/in6_pcb.h>
|
|
#include <netinet/tcp.h>
|
|
#include <netinet/tcp_fsm.h>
|
|
#include <netinet/tcp_seq.h>
|
|
#include <netinet/tcp_timer.h>
|
|
#include <netinet/tcp_var.h>
|
|
#include <netinet6/tcp6_var.h>
|
|
#include <netinet/tcpip.h>
|
|
#ifdef TCPDEBUG
|
|
#include <netinet/tcp_debug.h>
|
|
#endif /* TCPDEBUG */
|
|
|
|
#include <machine/in_cksum.h>
|
|
|
|
extern struct uma_zone *sack_hole_zone;
|
|
|
|
SYSCTL_NODE(_net_inet_tcp, OID_AUTO, sack, CTLFLAG_RW, 0, "TCP SACK");
|
|
int tcp_do_sack = 1;
|
|
SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, enable, CTLFLAG_RW,
|
|
&tcp_do_sack, 0, "Enable/Disable TCP SACK support");
|
|
TUNABLE_INT("net.inet.tcp.sack.enable", &tcp_do_sack);
|
|
|
|
static int tcp_sack_maxholes = 128;
|
|
SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, maxholes, CTLFLAG_RW,
|
|
&tcp_sack_maxholes, 0,
|
|
"Maximum number of TCP SACK holes allowed per connection");
|
|
|
|
static int tcp_sack_globalmaxholes = 65536;
|
|
SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, globalmaxholes, CTLFLAG_RW,
|
|
&tcp_sack_globalmaxholes, 0,
|
|
"Global maximum number of TCP SACK holes");
|
|
|
|
static int tcp_sack_globalholes = 0;
|
|
SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, globalholes, CTLFLAG_RD,
|
|
&tcp_sack_globalholes, 0,
|
|
"Global number of TCP SACK holes currently allocated");
|
|
|
|
/*
|
|
* This function is called upon receipt of new valid data (while not in header
|
|
* prediction mode), and it updates the ordered list of sacks.
|
|
*/
|
|
void
|
|
tcp_update_sack_list(struct tcpcb *tp, tcp_seq rcv_start, tcp_seq rcv_end)
|
|
{
|
|
/*
|
|
* First reported block MUST be the most recent one. Subsequent
|
|
* blocks SHOULD be in the order in which they arrived at the
|
|
* receiver. These two conditions make the implementation fully
|
|
* compliant with RFC 2018.
|
|
*/
|
|
struct sackblk head_blk, saved_blks[MAX_SACK_BLKS];
|
|
int num_head, num_saved, i;
|
|
|
|
INP_LOCK_ASSERT(tp->t_inpcb);
|
|
|
|
/* Check arguments */
|
|
KASSERT(SEQ_LT(rcv_start, rcv_end), ("rcv_start < rcv_end"));
|
|
|
|
/* SACK block for the received segment. */
|
|
head_blk.start = rcv_start;
|
|
head_blk.end = rcv_end;
|
|
|
|
/*
|
|
* Merge updated SACK blocks into head_blk, and
|
|
* save unchanged SACK blocks into saved_blks[].
|
|
* num_saved will have the number of the saved SACK blocks.
|
|
*/
|
|
num_saved = 0;
|
|
for (i = 0; i < tp->rcv_numsacks; i++) {
|
|
tcp_seq start = tp->sackblks[i].start;
|
|
tcp_seq end = tp->sackblks[i].end;
|
|
if (SEQ_GEQ(start, end) || SEQ_LEQ(start, tp->rcv_nxt)) {
|
|
/*
|
|
* Discard this SACK block.
|
|
*/
|
|
} else if (SEQ_LEQ(head_blk.start, end) &&
|
|
SEQ_GEQ(head_blk.end, start)) {
|
|
/*
|
|
* Merge this SACK block into head_blk.
|
|
* This SACK block itself will be discarded.
|
|
*/
|
|
if (SEQ_GT(head_blk.start, start))
|
|
head_blk.start = start;
|
|
if (SEQ_LT(head_blk.end, end))
|
|
head_blk.end = end;
|
|
} else {
|
|
/*
|
|
* Save this SACK block.
|
|
*/
|
|
saved_blks[num_saved].start = start;
|
|
saved_blks[num_saved].end = end;
|
|
num_saved++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Update SACK list in tp->sackblks[].
|
|
*/
|
|
num_head = 0;
|
|
if (SEQ_GT(head_blk.start, tp->rcv_nxt)) {
|
|
/*
|
|
* The received data segment is an out-of-order segment.
|
|
* Put head_blk at the top of SACK list.
|
|
*/
|
|
tp->sackblks[0] = head_blk;
|
|
num_head = 1;
|
|
/*
|
|
* If the number of saved SACK blocks exceeds its limit,
|
|
* discard the last SACK block.
|
|
*/
|
|
if (num_saved >= MAX_SACK_BLKS)
|
|
num_saved--;
|
|
}
|
|
if (num_saved > 0) {
|
|
/*
|
|
* Copy the saved SACK blocks back.
|
|
*/
|
|
bcopy(saved_blks, &tp->sackblks[num_head],
|
|
sizeof(struct sackblk) * num_saved);
|
|
}
|
|
|
|
/* Save the number of SACK blocks. */
|
|
tp->rcv_numsacks = num_head + num_saved;
|
|
}
|
|
|
|
/*
|
|
* Delete all receiver-side SACK information.
|
|
*/
|
|
void
|
|
tcp_clean_sackreport(tp)
|
|
struct tcpcb *tp;
|
|
{
|
|
int i;
|
|
|
|
INP_LOCK_ASSERT(tp->t_inpcb);
|
|
tp->rcv_numsacks = 0;
|
|
for (i = 0; i < MAX_SACK_BLKS; i++)
|
|
tp->sackblks[i].start = tp->sackblks[i].end=0;
|
|
}
|
|
|
|
/*
|
|
* Allocate struct sackhole.
|
|
*/
|
|
static struct sackhole *
|
|
tcp_sackhole_alloc(struct tcpcb *tp, tcp_seq start, tcp_seq end)
|
|
{
|
|
struct sackhole *hole;
|
|
|
|
if (tp->snd_numholes >= tcp_sack_maxholes ||
|
|
tcp_sack_globalholes >= tcp_sack_globalmaxholes) {
|
|
tcpstat.tcps_sack_sboverflow++;
|
|
return NULL;
|
|
}
|
|
|
|
hole = (struct sackhole *)uma_zalloc(sack_hole_zone, M_NOWAIT);
|
|
if (hole == NULL)
|
|
return NULL;
|
|
|
|
hole->start = start;
|
|
hole->end = end;
|
|
hole->rxmit = start;
|
|
|
|
tp->snd_numholes++;
|
|
tcp_sack_globalholes++;
|
|
|
|
return hole;
|
|
}
|
|
|
|
/*
|
|
* Free struct sackhole.
|
|
*/
|
|
static void
|
|
tcp_sackhole_free(struct tcpcb *tp, struct sackhole *hole)
|
|
{
|
|
uma_zfree(sack_hole_zone, hole);
|
|
|
|
tp->snd_numholes--;
|
|
tcp_sack_globalholes--;
|
|
|
|
KASSERT(tp->snd_numholes >= 0, ("tp->snd_numholes >= 0"));
|
|
KASSERT(tcp_sack_globalholes >= 0, ("tcp_sack_globalholes >= 0"));
|
|
}
|
|
|
|
/*
|
|
* Insert new SACK hole into scoreboard.
|
|
*/
|
|
static struct sackhole *
|
|
tcp_sackhole_insert(struct tcpcb *tp, tcp_seq start, tcp_seq end,
|
|
struct sackhole *after)
|
|
{
|
|
struct sackhole *hole;
|
|
|
|
/* Allocate a new SACK hole. */
|
|
hole = tcp_sackhole_alloc(tp, start, end);
|
|
if (hole == NULL)
|
|
return NULL;
|
|
|
|
/* Insert the new SACK hole into scoreboard */
|
|
if (after != NULL)
|
|
TAILQ_INSERT_AFTER(&tp->snd_holes, after, hole, scblink);
|
|
else
|
|
TAILQ_INSERT_TAIL(&tp->snd_holes, hole, scblink);
|
|
|
|
/* Update SACK hint. */
|
|
if (tp->sackhint.nexthole == NULL)
|
|
tp->sackhint.nexthole = hole;
|
|
|
|
return hole;
|
|
}
|
|
|
|
/*
|
|
* Remove SACK hole from scoreboard.
|
|
*/
|
|
static void
|
|
tcp_sackhole_remove(struct tcpcb *tp, struct sackhole *hole)
|
|
{
|
|
/* Update SACK hint. */
|
|
if (tp->sackhint.nexthole == hole)
|
|
tp->sackhint.nexthole = TAILQ_NEXT(hole, scblink);
|
|
|
|
/* Remove this SACK hole. */
|
|
TAILQ_REMOVE(&tp->snd_holes, hole, scblink);
|
|
|
|
/* Free this SACK hole. */
|
|
tcp_sackhole_free(tp, hole);
|
|
}
|
|
|
|
/*
|
|
* Process cumulative ACK and the TCP SACK option to update the scoreboard.
|
|
* tp->snd_holes is an ordered list of holes (oldest to newest, in terms of
|
|
* the sequence space).
|
|
*/
|
|
void
|
|
tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to, tcp_seq th_ack)
|
|
{
|
|
struct sackhole *cur, *temp;
|
|
struct sackblk sack, sack_blocks[TCP_MAX_SACK + 1], *sblkp;
|
|
int i, j, num_sack_blks;
|
|
|
|
INP_LOCK_ASSERT(tp->t_inpcb);
|
|
|
|
num_sack_blks = 0;
|
|
/*
|
|
* If SND.UNA will be advanced by SEG.ACK, and if SACK holes exist,
|
|
* treat [SND.UNA, SEG.ACK) as if it is a SACK block.
|
|
*/
|
|
if (SEQ_LT(tp->snd_una, th_ack) && !TAILQ_EMPTY(&tp->snd_holes)) {
|
|
sack_blocks[num_sack_blks].start = tp->snd_una;
|
|
sack_blocks[num_sack_blks++].end = th_ack;
|
|
}
|
|
/*
|
|
* Append received valid SACK blocks to sack_blocks[].
|
|
*/
|
|
for (i = 0; i < to->to_nsacks; i++) {
|
|
bcopy((to->to_sacks + i * TCPOLEN_SACK), &sack, sizeof(sack));
|
|
sack.start = ntohl(sack.start);
|
|
sack.end = ntohl(sack.end);
|
|
if (SEQ_GT(sack.end, sack.start) &&
|
|
SEQ_GT(sack.start, tp->snd_una) &&
|
|
SEQ_GT(sack.start, th_ack) &&
|
|
SEQ_LT(sack.start, tp->snd_max) &&
|
|
SEQ_GT(sack.end, tp->snd_una) &&
|
|
SEQ_LEQ(sack.end, tp->snd_max))
|
|
sack_blocks[num_sack_blks++] = sack;
|
|
}
|
|
|
|
/*
|
|
* Return if SND.UNA is not advanced and no valid SACK block
|
|
* is received.
|
|
*/
|
|
if (num_sack_blks == 0)
|
|
return;
|
|
|
|
/*
|
|
* Sort the SACK blocks so we can update the scoreboard
|
|
* with just one pass. The overhead of sorting upto 4+1 elements
|
|
* is less than making upto 4+1 passes over the scoreboard.
|
|
*/
|
|
for (i = 0; i < num_sack_blks; i++) {
|
|
for (j = i + 1; j < num_sack_blks; j++) {
|
|
if (SEQ_GT(sack_blocks[i].end, sack_blocks[j].end)) {
|
|
sack = sack_blocks[i];
|
|
sack_blocks[i] = sack_blocks[j];
|
|
sack_blocks[j] = sack;
|
|
}
|
|
}
|
|
}
|
|
if (TAILQ_EMPTY(&tp->snd_holes))
|
|
/*
|
|
* Empty scoreboard. Need to initialize snd_fack (it may be
|
|
* uninitialized or have a bogus value). Scoreboard holes
|
|
* (from the sack blocks received) are created later below (in
|
|
* the logic that adds holes to the tail of the scoreboard).
|
|
*/
|
|
tp->snd_fack = SEQ_MAX(tp->snd_una, th_ack);
|
|
/*
|
|
* In the while-loop below, incoming SACK blocks (sack_blocks[])
|
|
* and SACK holes (snd_holes) are traversed from their tails with
|
|
* just one pass in order to reduce the number of compares especially
|
|
* when the bandwidth-delay product is large.
|
|
* Note: Typically, in the first RTT of SACK recovery, the highest
|
|
* three or four SACK blocks with the same ack number are received.
|
|
* In the second RTT, if retransmitted data segments are not lost,
|
|
* the highest three or four SACK blocks with ack number advancing
|
|
* are received.
|
|
*/
|
|
sblkp = &sack_blocks[num_sack_blks - 1]; /* Last SACK block */
|
|
if (SEQ_LT(tp->snd_fack, sblkp->start)) {
|
|
/*
|
|
* The highest SACK block is beyond fack.
|
|
* Append new SACK hole at the tail.
|
|
* If the second or later highest SACK blocks are also
|
|
* beyond the current fack, they will be inserted by
|
|
* way of hole splitting in the while-loop below.
|
|
*/
|
|
temp = tcp_sackhole_insert(tp, tp->snd_fack,sblkp->start,NULL);
|
|
if (temp != NULL) {
|
|
tp->snd_fack = sblkp->end;
|
|
/* Go to the previous sack block. */
|
|
sblkp--;
|
|
} else {
|
|
/*
|
|
* We failed to add a new hole based on the current
|
|
* sack block. Skip over all the sack blocks that
|
|
* fall completely to the right of snd_fack and proceed
|
|
* to trim the scoreboard based on the remaining sack
|
|
* blocks. This also trims the scoreboard for th_ack
|
|
* (which is sack_blocks[0]).
|
|
*/
|
|
while (sblkp >= sack_blocks &&
|
|
SEQ_LT(tp->snd_fack, sblkp->start))
|
|
sblkp--;
|
|
if (sblkp >= sack_blocks &&
|
|
SEQ_LT(tp->snd_fack, sblkp->end))
|
|
tp->snd_fack = sblkp->end;
|
|
}
|
|
} else if (SEQ_LT(tp->snd_fack, sblkp->end))
|
|
/* fack is advanced. */
|
|
tp->snd_fack = sblkp->end;
|
|
/* We must have at least one SACK hole in scoreboard */
|
|
KASSERT(!TAILQ_EMPTY(&tp->snd_holes), ("SACK scoreboard must not be empty"));
|
|
cur = TAILQ_LAST(&tp->snd_holes, sackhole_head); /* Last SACK hole */
|
|
/*
|
|
* Since the incoming sack blocks are sorted, we can process them
|
|
* making one sweep of the scoreboard.
|
|
*/
|
|
while (sblkp >= sack_blocks && cur != NULL) {
|
|
if (SEQ_GEQ(sblkp->start, cur->end)) {
|
|
/*
|
|
* SACKs data beyond the current hole.
|
|
* Go to the previous sack block.
|
|
*/
|
|
sblkp--;
|
|
continue;
|
|
}
|
|
if (SEQ_LEQ(sblkp->end, cur->start)) {
|
|
/*
|
|
* SACKs data before the current hole.
|
|
* Go to the previous hole.
|
|
*/
|
|
cur = TAILQ_PREV(cur, sackhole_head, scblink);
|
|
continue;
|
|
}
|
|
tp->sackhint.sack_bytes_rexmit -= (cur->rxmit - cur->start);
|
|
KASSERT(tp->sackhint.sack_bytes_rexmit >= 0,
|
|
("sackhint bytes rtx >= 0"));
|
|
if (SEQ_LEQ(sblkp->start, cur->start)) {
|
|
/* Data acks at least the beginning of hole */
|
|
if (SEQ_GEQ(sblkp->end, cur->end)) {
|
|
/* Acks entire hole, so delete hole */
|
|
temp = cur;
|
|
cur = TAILQ_PREV(cur, sackhole_head, scblink);
|
|
tcp_sackhole_remove(tp, temp);
|
|
/*
|
|
* The sack block may ack all or part of the next
|
|
* hole too, so continue onto the next hole.
|
|
*/
|
|
continue;
|
|
} else {
|
|
/* Move start of hole forward */
|
|
cur->start = sblkp->end;
|
|
cur->rxmit = SEQ_MAX(cur->rxmit, cur->start);
|
|
}
|
|
} else {
|
|
/* Data acks at least the end of hole */
|
|
if (SEQ_GEQ(sblkp->end, cur->end)) {
|
|
/* Move end of hole backward */
|
|
cur->end = sblkp->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_insert(tp, sblkp->end,
|
|
cur->end, cur);
|
|
if (temp != NULL) {
|
|
if (SEQ_GT(cur->rxmit, temp->rxmit)) {
|
|
temp->rxmit = cur->rxmit;
|
|
tp->sackhint.sack_bytes_rexmit
|
|
+= (temp->rxmit
|
|
- temp->start);
|
|
}
|
|
cur->end = sblkp->start;
|
|
cur->rxmit = SEQ_MIN(cur->rxmit,
|
|
cur->end);
|
|
}
|
|
}
|
|
}
|
|
tp->sackhint.sack_bytes_rexmit += (cur->rxmit - cur->start);
|
|
/*
|
|
* Testing sblkp->start against cur->start tells us whether
|
|
* we're done with the sack block or the sack hole.
|
|
* Accordingly, we advance one or the other.
|
|
*/
|
|
if (SEQ_LEQ(sblkp->start, cur->start))
|
|
cur = TAILQ_PREV(cur, sackhole_head, scblink);
|
|
else
|
|
sblkp--;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Free all SACK holes to clear the scoreboard.
|
|
*/
|
|
void
|
|
tcp_free_sackholes(struct tcpcb *tp)
|
|
{
|
|
struct sackhole *q;
|
|
|
|
INP_LOCK_ASSERT(tp->t_inpcb);
|
|
while ((q = TAILQ_FIRST(&tp->snd_holes)) != NULL)
|
|
tcp_sackhole_remove(tp, q);
|
|
tp->sackhint.sack_bytes_rexmit = 0;
|
|
|
|
KASSERT(tp->snd_numholes == 0, ("tp->snd_numholes == 0"));
|
|
KASSERT(tp->sackhint.nexthole == NULL,
|
|
("tp->sackhint.nexthole == NULL"));
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
|
|
#if 0
|
|
/*
|
|
* 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);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* 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;
|
|
|
|
INP_LOCK_ASSERT(tp->t_inpcb);
|
|
*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:
|
|
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->snd_fack))
|
|
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 snd_fack
|
|
*/
|
|
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->snd_fack;
|
|
return;
|
|
}
|