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[TCP]: Advance fast path pointer for first block only 

Only advance the SACK fast-path pointer for the first block, the
fast-path assumes that only the first block advances next time so we
should not move the cached skb for the next sack blocks.

Signed-off-by: Baruch Even <baruch@ev-en.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Baruch Even 2007-02-04 23:35:57 -08:00 committed by David S. Miller
parent ffbc61117d
commit fda03fbb56
1 changed files with 24 additions and 10 deletions
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34
net/ipv4/tcp_input.c
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@ -936,13 +936,16 @@ 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 = ack_skb->h.raw + TCP_SKB_CB(ack_skb)->sacked;
struct tcp_sack_block_wire *sp = (struct tcp_sack_block_wire *)(ptr+2);
struct sk_buff *cached_skb;
int num_sacks = (ptr[1] - TCPOLEN_SACK_BASE)>>3;
int reord = tp->packets_out;
int prior_fackets;
u32 lost_retrans = 0;
int flag = 0;
int dup_sack = 0;
int cached_fack_count;
int i;
int first_sack_index;
if (!tp->sacked_out)
tp->fackets_out = 0;
@ -1000,6 +1003,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
}
}
first_sack_index = 0;
if (flag)
num_sacks = 1;
else {
@ -1016,6 +1020,10 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
tmp = sp[j];
sp[j] = sp[j+1];
sp[j+1] = tmp;
/* Track where the first SACK block goes to */
if (j == first_sack_index)
first_sack_index = j+1;
}
}
@ -1025,20 +1033,22 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
/* clear flag as used for different purpose in following code */
flag = 0;
/* Use SACK fastpath hint if valid */
cached_skb = tp->fastpath_skb_hint;
cached_fack_count = tp->fastpath_cnt_hint;
if (!cached_skb) {
cached_skb = sk->sk_write_queue.next;
cached_fack_count = 0;
}
for (i=0; i<num_sacks; i++, sp++) {
struct sk_buff *skb;
__u32 start_seq = ntohl(sp->start_seq);
__u32 end_seq = ntohl(sp->end_seq);
int fack_count;
/* Use SACK fastpath hint if valid */
if (tp->fastpath_skb_hint) {
skb = tp->fastpath_skb_hint;
fack_count = tp->fastpath_cnt_hint;
} else {
skb = sk->sk_write_queue.next;
fack_count = 0;
}
skb = cached_skb;
fack_count = cached_fack_count;
/* Event "B" in the comment above. */
if (after(end_seq, tp->high_seq))
@ -1048,8 +1058,12 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
int in_sack, pcount;
u8 sacked;
tp->fastpath_skb_hint = skb;
tp->fastpath_cnt_hint = fack_count;
cached_skb = skb;
cached_fack_count = fack_count;
if (i == first_sack_index) {
tp->fastpath_skb_hint = skb;
tp->fastpath_cnt_hint = fack_count;
}
/* The retransmission queue is always in order, so
* we can short-circuit the walk early.