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[TCP]: Earlier SACK block verification & simplify access to them
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Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Ilpo Järvinen authored and David S. Miller committed Jan 28, 2008
1 parent 9e10c47 commit fd6dad6
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Showing 2 changed files with 52 additions and 35 deletions.
2 changes: 1 addition & 1 deletion include/linux/tcp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -330,7 +330,7 @@ struct tcp_sock {
struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/

struct tcp_sack_block_wire recv_sack_cache[4];
struct tcp_sack_block recv_sack_cache[4];

struct sk_buff *highest_sack; /* highest skb with SACK received
* (validity guaranteed only if
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85 changes: 51 additions & 34 deletions net/ipv4/tcp_input.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1340,9 +1340,11 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
struct tcp_sock *tp = tcp_sk(sk);
unsigned char *ptr = (skb_transport_header(ack_skb) +
TCP_SKB_CB(ack_skb)->sacked);
struct tcp_sack_block_wire *sp = (struct tcp_sack_block_wire *)(ptr+2);
struct tcp_sack_block_wire *sp_wire = (struct tcp_sack_block_wire *)(ptr+2);
struct tcp_sack_block sp[4];
struct sk_buff *cached_skb;
int num_sacks = (ptr[1] - TCPOLEN_SACK_BASE)>>3;
int used_sacks;
int reord = tp->packets_out;
int flag = 0;
int found_dup_sack = 0;
Expand All @@ -1357,7 +1359,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
tp->highest_sack = tcp_write_queue_head(sk);
}

found_dup_sack = tcp_check_dsack(tp, ack_skb, sp,
found_dup_sack = tcp_check_dsack(tp, ack_skb, sp_wire,
num_sacks, prior_snd_una);
if (found_dup_sack)
flag |= FLAG_DSACKING_ACK;
Expand All @@ -1372,14 +1374,49 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
if (!tp->packets_out)
goto out;

used_sacks = 0;
first_sack_index = 0;
for (i = 0; i < num_sacks; i++) {
int dup_sack = !i && found_dup_sack;

sp[used_sacks].start_seq = ntohl(get_unaligned(&sp_wire[i].start_seq));
sp[used_sacks].end_seq = ntohl(get_unaligned(&sp_wire[i].end_seq));

if (!tcp_is_sackblock_valid(tp, dup_sack,
sp[used_sacks].start_seq,
sp[used_sacks].end_seq)) {
if (dup_sack) {
if (!tp->undo_marker)
NET_INC_STATS_BH(LINUX_MIB_TCPDSACKIGNOREDNOUNDO);
else
NET_INC_STATS_BH(LINUX_MIB_TCPDSACKIGNOREDOLD);
} else {
/* Don't count olds caused by ACK reordering */
if ((TCP_SKB_CB(ack_skb)->ack_seq != tp->snd_una) &&
!after(sp[used_sacks].end_seq, tp->snd_una))
continue;
NET_INC_STATS_BH(LINUX_MIB_TCPSACKDISCARD);
}
if (i == 0)
first_sack_index = -1;
continue;
}

/* Ignore very old stuff early */
if (!after(sp[used_sacks].end_seq, prior_snd_una))
continue;

used_sacks++;
}

/* SACK fastpath:
* if the only SACK change is the increase of the end_seq of
* the first block then only apply that SACK block
* and use retrans queue hinting otherwise slowpath */
force_one_sack = 1;
for (i = 0; i < num_sacks; i++) {
__be32 start_seq = sp[i].start_seq;
__be32 end_seq = sp[i].end_seq;
for (i = 0; i < used_sacks; i++) {
u32 start_seq = sp[i].start_seq;
u32 end_seq = sp[i].end_seq;

if (i == 0) {
if (tp->recv_sack_cache[i].start_seq != start_seq)
Expand All @@ -1398,19 +1435,17 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
tp->recv_sack_cache[i].end_seq = 0;
}

first_sack_index = 0;
if (force_one_sack)
num_sacks = 1;
used_sacks = 1;
else {
int j;
tp->fastpath_skb_hint = NULL;

/* order SACK blocks to allow in order walk of the retrans queue */
for (i = num_sacks-1; i > 0; i--) {
for (i = used_sacks - 1; i > 0; i--) {
for (j = 0; j < i; j++){
if (after(ntohl(sp[j].start_seq),
ntohl(sp[j+1].start_seq))){
struct tcp_sack_block_wire tmp;
if (after(sp[j].start_seq, sp[j+1].start_seq)) {
struct tcp_sack_block tmp;

tmp = sp[j];
sp[j] = sp[j+1];
Expand All @@ -1433,32 +1468,14 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
cached_fack_count = 0;
}

for (i = 0; i < num_sacks; i++) {
for (i = 0; i < used_sacks; i++) {
struct sk_buff *skb;
__u32 start_seq = ntohl(sp->start_seq);
__u32 end_seq = ntohl(sp->end_seq);
u32 start_seq = sp[i].start_seq;
u32 end_seq = sp[i].end_seq;
int fack_count;
int dup_sack = (found_dup_sack && (i == first_sack_index));
int next_dup = (found_dup_sack && (i+1 == first_sack_index));

sp++;

if (!tcp_is_sackblock_valid(tp, dup_sack, start_seq, end_seq)) {
if (dup_sack) {
if (!tp->undo_marker)
NET_INC_STATS_BH(LINUX_MIB_TCPDSACKIGNOREDNOUNDO);
else
NET_INC_STATS_BH(LINUX_MIB_TCPDSACKIGNOREDOLD);
} else {
/* Don't count olds caused by ACK reordering */
if ((TCP_SKB_CB(ack_skb)->ack_seq != tp->snd_una) &&
!after(end_seq, tp->snd_una))
continue;
NET_INC_STATS_BH(LINUX_MIB_TCPSACKDISCARD);
}
continue;
}

skb = cached_skb;
fack_count = cached_fack_count;

Expand Down Expand Up @@ -1489,8 +1506,8 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_

/* Due to sorting DSACK may reside within this SACK block! */
if (next_dup) {
u32 dup_start = ntohl(sp->start_seq);
u32 dup_end = ntohl(sp->end_seq);
u32 dup_start = sp[i+1].start_seq;
u32 dup_end = sp[i+1].end_seq;

if (before(TCP_SKB_CB(skb)->seq, dup_end)) {
in_sack = tcp_match_skb_to_sack(sk, skb, dup_start, dup_end);
Expand Down

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