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Message-Id: <11921053181239-git-send-email-ilpo.jarvinen@helsinki.fi>
Date: Thu, 11 Oct 2007 15:21:53 +0300
From: "Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org, TAKANO Ryousei <takano@...-inc.co.jp>,
--cc@...helsinki.fi, "David S.Miller" <davem@...emloft.net>
Subject: [PATCH 1/6] [TCP]: Create tcp_sacktag_state.
From: David S. Miller <davem@...emloft.net>
It is difficult to break out the inner-logic of
tcp_sacktag_write_queue() into worker functions because
so many local variables get updated in-place.
Start to overcome this by creating a structure block
of state variables that can be passed around into
worker routines.
[I made minor tweaks due to rebase/reordering of stuff
in tcp-2.6 tree, and dropped found_dup_sack & dup_sack
from state -ij]
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...sinki.fi>
---
net/ipv4/tcp_input.c | 82 +++++++++++++++++++++++++++-----------------------
1 files changed, 44 insertions(+), 38 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 0a42e93..1f6cbce 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1165,6 +1165,14 @@ static int tcp_mark_lost_retrans(struct sock *sk, u32 received_upto)
return flag;
}
+struct tcp_sacktag_state {
+ unsigned int flag;
+ int reord;
+ int prior_fackets;
+ u32 highest_sack_end_seq;
+ int first_sack_index;
+};
+
static int tcp_check_dsack(struct tcp_sock *tp, struct sk_buff *ack_skb,
struct tcp_sack_block_wire *sp, int num_sacks,
u32 prior_snd_una)
@@ -1240,26 +1248,23 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
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 highest_sack_end_seq = 0;
- int flag = 0;
- int found_dup_sack = 0;
+ struct tcp_sacktag_state state;
+ int found_dup_sack;
int cached_fack_count;
int i;
- int first_sack_index;
+ int force_one_sack;
+
+ state.flag = 0;
if (!tp->sacked_out) {
if (WARN_ON(tp->fackets_out))
tp->fackets_out = 0;
tp->highest_sack = tp->snd_una;
}
- prior_fackets = tp->fackets_out;
- found_dup_sack = tcp_check_dsack(tp, ack_skb, sp,
- num_sacks, prior_snd_una);
+ found_dup_sack = tcp_check_dsack(tp, ack_skb, sp, num_sacks, prior_snd_una);
if (found_dup_sack)
- flag |= FLAG_DSACKING_ACK;
+ state.flag |= FLAG_DSACKING_ACK;
/* Eliminate too old ACKs, but take into
* account more or less fresh ones, they can
@@ -1272,18 +1277,18 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
* 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 */
- flag = 1;
+ 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;
if (i == 0) {
if (tp->recv_sack_cache[i].start_seq != start_seq)
- flag = 0;
+ force_one_sack = 0;
} else {
if ((tp->recv_sack_cache[i].start_seq != start_seq) ||
(tp->recv_sack_cache[i].end_seq != end_seq))
- flag = 0;
+ force_one_sack = 0;
}
tp->recv_sack_cache[i].start_seq = start_seq;
tp->recv_sack_cache[i].end_seq = end_seq;
@@ -1294,8 +1299,8 @@ 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 (flag)
+ state.first_sack_index = 0;
+ if (force_one_sack)
num_sacks = 1;
else {
int j;
@@ -1313,17 +1318,14 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
sp[j+1] = tmp;
/* Track where the first SACK block goes to */
- if (j == first_sack_index)
- first_sack_index = j+1;
+ if (j == state.first_sack_index)
+ state.first_sack_index = j+1;
}
}
}
}
- /* 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;
@@ -1332,12 +1334,16 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
cached_fack_count = 0;
}
+ state.reord = tp->packets_out;
+ state.prior_fackets = tp->fackets_out;
+ state.highest_sack_end_seq = 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;
- int dup_sack = (found_dup_sack && (i == first_sack_index));
+ int dup_sack = (found_dup_sack && (i == state.first_sack_index));
if (!tcp_is_sackblock_valid(tp, dup_sack, start_seq, end_seq)) {
if (dup_sack) {
@@ -1360,7 +1366,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
/* Event "B" in the comment above. */
if (after(end_seq, tp->high_seq))
- flag |= FLAG_DATA_LOST;
+ state.flag |= FLAG_DATA_LOST;
tcp_for_write_queue_from(skb, sk) {
int in_sack;
@@ -1371,7 +1377,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
cached_skb = skb;
cached_fack_count = fack_count;
- if (i == first_sack_index) {
+ if (i == state.first_sack_index) {
tp->fastpath_skb_hint = skb;
tp->fastpath_cnt_hint = fack_count;
}
@@ -1401,12 +1407,12 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
if (sacked&TCPCB_RETRANS) {
if ((dup_sack && in_sack) &&
(sacked&TCPCB_SACKED_ACKED))
- reord = min(fack_count, reord);
+ state.reord = min(fack_count, state.reord);
} else {
/* If it was in a hole, we detected reordering. */
- if (fack_count < prior_fackets &&
+ if (fack_count < state.prior_fackets &&
!(sacked&TCPCB_SACKED_ACKED))
- reord = min(fack_count, reord);
+ state.reord = min(fack_count, state.reord);
}
/* Nothing to do; acked frame is about to be dropped. */
@@ -1435,8 +1441,8 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
* which was in hole. It is reordering.
*/
if (!(sacked & TCPCB_RETRANS) &&
- fack_count < prior_fackets)
- reord = min(fack_count, reord);
+ fack_count < state.prior_fackets)
+ state.reord = min(fack_count, state.reord);
if (sacked & TCPCB_LOST) {
TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
@@ -1452,15 +1458,15 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
* Clearing correct due to in-order walk
*/
if (after(end_seq, tp->frto_highmark)) {
- flag &= ~FLAG_ONLY_ORIG_SACKED;
+ state.flag &= ~FLAG_ONLY_ORIG_SACKED;
} else {
if (!(sacked & TCPCB_RETRANS))
- flag |= FLAG_ONLY_ORIG_SACKED;
+ state.flag |= FLAG_ONLY_ORIG_SACKED;
}
}
TCP_SKB_CB(skb)->sacked |= TCPCB_SACKED_ACKED;
- flag |= FLAG_DATA_SACKED;
+ state.flag |= FLAG_DATA_SACKED;
tp->sacked_out += tcp_skb_pcount(skb);
if (fack_count > tp->fackets_out)
@@ -1468,11 +1474,11 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
if (after(TCP_SKB_CB(skb)->seq, tp->highest_sack)) {
tp->highest_sack = TCP_SKB_CB(skb)->seq;
- highest_sack_end_seq = TCP_SKB_CB(skb)->end_seq;
+ state.highest_sack_end_seq = TCP_SKB_CB(skb)->end_seq;
}
} else {
if (dup_sack && (sacked&TCPCB_RETRANS))
- reord = min(fack_count, reord);
+ state.reord = min(fack_count, state.reord);
}
/* D-SACK. We can detect redundant retransmission
@@ -1490,15 +1496,15 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
}
if (tp->retrans_out &&
- after(highest_sack_end_seq, tp->lost_retrans_low) &&
+ after(state.highest_sack_end_seq, tp->lost_retrans_low) &&
icsk->icsk_ca_state == TCP_CA_Recovery)
- flag |= tcp_mark_lost_retrans(sk, highest_sack_end_seq);
+ state.flag |= tcp_mark_lost_retrans(sk, state.highest_sack_end_seq);
tcp_verify_left_out(tp);
- if ((reord < tp->fackets_out) && icsk->icsk_ca_state != TCP_CA_Loss &&
+ if ((state.reord < tp->fackets_out) && icsk->icsk_ca_state != TCP_CA_Loss &&
(!tp->frto_highmark || after(tp->snd_una, tp->frto_highmark)))
- tcp_update_reordering(sk, ((tp->fackets_out + 1) - reord), 0);
+ tcp_update_reordering(sk, ((tp->fackets_out + 1) - state.reord), 0);
#if FASTRETRANS_DEBUG > 0
BUG_TRAP((int)tp->sacked_out >= 0);
@@ -1506,7 +1512,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
BUG_TRAP((int)tp->retrans_out >= 0);
BUG_TRAP((int)tcp_packets_in_flight(tp) >= 0);
#endif
- return flag;
+ return state.flag;
}
/* If we receive more dupacks than we expected counting segments
--
1.5.0.6
-
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