diff --git a/sys/netinet/tcp_sack.c b/sys/netinet/tcp_sack.c index 807526f4a843..aa0849ccf94e 100644 --- a/sys/netinet/tcp_sack.c +++ b/sys/netinet/tcp_sack.c @@ -1,6 +1,7 @@ /*- * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 - * The Regents of the University of California. All rights reserved. + * 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 @@ -27,37 +28,9 @@ * 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 @@ -96,6 +69,10 @@ * official policies, either expressed or implied, of the US Naval * Research Laboratory (NRL). */ + +#include +__FBSDID("$FreeBSD$"); + #include "opt_inet.h" #include "opt_inet6.h" #include "opt_tcpdebug.h" @@ -168,8 +145,8 @@ SYSCTL_INT(_net_inet_tcp_sack, OID_AUTO, globalholes, CTLFLAG_RD, "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. + * 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) @@ -185,7 +162,7 @@ tcp_update_sack_list(struct tcpcb *tp, tcp_seq rcv_start, tcp_seq rcv_end) INP_LOCK_ASSERT(tp->t_inpcb); - /* Check arguments */ + /* Check arguments. */ KASSERT(SEQ_LT(rcv_start, rcv_end), ("rcv_start < rcv_end")); /* SACK block for the received segment. */ @@ -193,9 +170,9 @@ tcp_update_sack_list(struct tcpcb *tp, tcp_seq rcv_start, tcp_seq rcv_end) 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. + * 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++) { @@ -208,8 +185,8 @@ tcp_update_sack_list(struct tcpcb *tp, tcp_seq rcv_start, tcp_seq rcv_end) } 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. + * 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; @@ -231,8 +208,8 @@ tcp_update_sack_list(struct tcpcb *tp, tcp_seq rcv_start, tcp_seq rcv_end) 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. + * 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; @@ -303,6 +280,7 @@ tcp_sackhole_alloc(struct tcpcb *tp, tcp_seq start, tcp_seq end) static void tcp_sackhole_free(struct tcpcb *tp, struct sackhole *hole) { + uma_zfree(sack_hole_zone, hole); tp->snd_numholes--; @@ -326,7 +304,7 @@ tcp_sackhole_insert(struct tcpcb *tp, tcp_seq start, tcp_seq end, if (hole == NULL) return NULL; - /* Insert the new SACK hole into scoreboard */ + /* Insert the new SACK hole into scoreboard. */ if (after != NULL) TAILQ_INSERT_AFTER(&tp->snd_holes, after, hole, scblink); else @@ -345,6 +323,7 @@ tcp_sackhole_insert(struct tcpcb *tp, tcp_seq start, tcp_seq end, 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); @@ -380,8 +359,8 @@ tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to, tcp_seq th_ack) sack_blocks[num_sack_blks++].end = th_ack; } /* - * Append received valid SACK blocks to sack_blocks[], but only - * if we received new blocks from the other side. + * Append received valid SACK blocks to sack_blocks[], but only if we + * received new blocks from the other side. */ if (to->to_flags & TOF_SACK) { for (i = 0; i < to->to_nsacks; i++) { @@ -399,16 +378,16 @@ tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to, tcp_seq th_ack) } } /* - * Return if SND.UNA is not advanced and no valid SACK block - * is received. + * 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. + * 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++) { @@ -423,15 +402,17 @@ tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to, tcp_seq th_ack) /* * 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). + * (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. + * 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, @@ -441,11 +422,10 @@ tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to, tcp_seq th_ack) 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. + * 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) { @@ -456,10 +436,10 @@ tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to, tcp_seq th_ack) /* * 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]). + * 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)) @@ -471,9 +451,10 @@ tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to, tcp_seq th_ack) } 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 */ + /* 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. @@ -481,63 +462,64 @@ tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to, tcp_seq th_ack) 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. + * 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. + * 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")); + ("sackhint bytes rtx >= 0")); if (SEQ_LEQ(sblkp->start, cur->start)) { - /* Data acks at least the beginning of hole */ + /* Data acks at least the beginning of hole. */ if (SEQ_GEQ(sblkp->end, cur->end)) { - /* Acks entire hole, so delete hole */ + /* 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. + * 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 */ + /* 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 */ + /* Data acks at least the end of hole. */ if (SEQ_GEQ(sblkp->end, cur->end)) { - /* Move end of hole backward */ + /* 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 + * ACKs some data in middle of a hole; need + * to split current hole */ temp = tcp_sackhole_insert(tp, sblkp->end, - cur->end, cur); + 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); + += (temp->rxmit + - temp->start); } cur->end = sblkp->start; cur->rxmit = SEQ_MIN(cur->rxmit, - cur->end); + cur->end); } } } @@ -573,14 +555,12 @@ tcp_free_sackholes(struct tcpcb *tp) } /* - * 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. + * 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(struct tcpcb *tp, struct tcphdr *th) @@ -590,12 +570,11 @@ tcp_sack_partialack(struct tcpcb *tp, struct tcphdr *th) INP_LOCK_ASSERT(tp->t_inpcb); tcp_timer_activate(tp, TT_REXMT, 0); tp->t_rtttime = 0; - /* send one or 2 segments based on how much new data was acked */ + /* 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); + (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; @@ -604,7 +583,7 @@ tcp_sack_partialack(struct tcpcb *tp, struct tcphdr *th) #if 0 /* - * Debug version of tcp_sack_output() that walks the scoreboard. Used for + * Debug version of tcp_sack_output() that walks the scoreboard. Used for * now to sanity check the hint. */ static struct sackhole * @@ -630,20 +609,20 @@ tcp_sack_output_debug(struct tcpcb *tp, int *sack_bytes_rexmt) /* * 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 + * 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. + * 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. + * 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) @@ -680,7 +659,7 @@ tcp_sack_adjust(struct tcpcb *tp) 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