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tcp: kill pointless urg_mode

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It all started from me noticing that this urgent check in
tcp_clean_rtx_queue is unnecessarily inside the loop. Then
I took a longer look to it and found out that the users of
urg_mode can trivially do without, well almost, there was
one gotcha.

Bonus: those funny people who use urg with >= 2^31 write_seq -
snd_una could now rejoice too (that's the only purpose for the
between being there, otherwise a simple compare would have done
the thing). Not that I assume that the rest of the tcp code
happily lives with such mind-boggling numbers :-). Alas, it
turned out to be impossible to set wmem to such numbers anyway,
yes I really tried a big sendfile after setting some wmem but
nothing happened :-). ...Tcp_wmem is int and so is sk_sndbuf...
So I hacked a bit variable to long and found out that it seems
to work... :-)

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ilpo Järvinen 2008-10-07 14:43:06 -07:00 committed by David S. Miller
parent 654bed16cf
commit 33f5f57eeb
5 changed files with 24 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/linux/tcp.h
View File

@ -312,8 +312,11 @@ struct tcp_sock {
u32 retrans_out; /* Retransmitted packets out */
u16 urg_data; /* Saved octet of OOB data and control flags */
u8 urg_mode; /* In urgent mode */
u8 ecn_flags; /* ECN status bits. */
u8 reordering; /* Packet reordering metric. */
u32 snd_up; /* Urgent pointer */
u8 keepalive_probes; /* num of allowed keep alive probes */
/*
* Options received (usually on last packet, some only on SYN packets).
*/
@ -361,8 +364,6 @@ struct tcp_sock {
u32 lost_retrans_low; /* Sent seq after any rxmit (lowest) */
u8 reordering; /* Packet reordering metric. */
u8 keepalive_probes; /* num of allowed keep alive probes */
u32 prior_ssthresh; /* ssthresh saved at recovery start */
u32 high_seq; /* snd_nxt at onset of congestion */
@ -374,8 +375,6 @@ struct tcp_sock {
u32 total_retrans; /* Total retransmits for entire connection */
u32 urg_seq; /* Seq of received urgent pointer */
u32 snd_up; /* Urgent pointer */
unsigned int keepalive_time; /* time before keep alive takes place */
unsigned int keepalive_intvl; /* time interval between keep alive probes */

4
net/ipv4/tcp.c
View File

@ -497,10 +497,8 @@ static inline void skb_entail(struct sock *sk, struct sk_buff *skb)
static inline void tcp_mark_urg(struct tcp_sock *tp, int flags,
struct sk_buff *skb)
{
if (flags & MSG_OOB) {
tp->urg_mode = 1;
if (flags & MSG_OOB)
tp->snd_up = tp->write_seq;
}
}
static inline void tcp_push(struct sock *sk, int flags, int mss_now,

11
net/ipv4/tcp_input.c
View File

@ -2836,7 +2836,8 @@ static u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb)
* is before the ack sequence we can discard it as it's confirmed to have
* arrived at the other end.
*/
static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets)
static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
u32 prior_snd_una)
{
struct tcp_sock *tp = tcp_sk(sk);
const struct inet_connection_sock *icsk = inet_csk(sk);
@ -2903,9 +2904,6 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets)
if (sacked & TCPCB_LOST)
tp->lost_out -= acked_pcount;
if (unlikely(tp->urg_mode && !before(end_seq, tp->snd_up)))
tp->urg_mode = 0;
tp->packets_out -= acked_pcount;
pkts_acked += acked_pcount;
@ -2935,6 +2933,9 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets)
tp->lost_skb_hint = NULL;
}
if (likely(between(tp->snd_up, prior_snd_una, tp->snd_una)))
tp->snd_up = tp->snd_una;
if (skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
flag |= FLAG_SACK_RENEGING;
@ -3311,7 +3312,7 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
goto no_queue;
/* See if we can take anything off of the retransmit queue. */
flag |= tcp_clean_rtx_queue(sk, prior_fackets);
flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una);
if (tp->frto_counter)
frto_cwnd = tcp_process_frto(sk, flag);

1
net/ipv4/tcp_minisocks.c
View File

@ -395,6 +395,7 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
newtp->pred_flags = 0;
newtp->rcv_wup = newtp->copied_seq = newtp->rcv_nxt = treq->rcv_isn + 1;
newtp->snd_sml = newtp->snd_una = newtp->snd_nxt = treq->snt_isn + 1;
newtp->snd_up = treq->snt_isn + 1;
tcp_prequeue_init(newtp);

18
net/ipv4/tcp_output.c
View File

@ -345,6 +345,11 @@ static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
TCP_SKB_CB(skb)->end_seq = seq;
}
static inline int tcp_urg_mode(const struct tcp_sock *tp)
{
return tp->snd_una != tp->snd_up;
}
#define OPTION_SACK_ADVERTISE (1 << 0)
#define OPTION_TS (1 << 1)
#define OPTION_MD5 (1 << 2)
@ -646,7 +651,8 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
th->check = 0;
th->urg_ptr = 0;
if (unlikely(tp->urg_mode &&
/* The urg_mode check is necessary during a below snd_una win probe */
if (unlikely(tcp_urg_mode(tp) &&
between(tp->snd_up, tcb->seq + 1, tcb->seq + 0xFFFF))) {
th->urg_ptr = htons(tp->snd_up - tcb->seq);
th->urg = 1;
@ -1012,7 +1018,7 @@ unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu)
/* Compute the current effective MSS, taking SACKs and IP options,
* and even PMTU discovery events into account.
*
* LARGESEND note: !urg_mode is overkill, only frames up to snd_up
* LARGESEND note: !tcp_urg_mode is overkill, only frames up to snd_up
* cannot be large. However, taking into account rare use of URG, this
* is not a big flaw.
*/
@ -1029,7 +1035,7 @@ unsigned int tcp_current_mss(struct sock *sk, int large_allowed)
mss_now = tp->mss_cache;
if (large_allowed && sk_can_gso(sk) && !tp->urg_mode)
if (large_allowed && sk_can_gso(sk) && !tcp_urg_mode(tp))
doing_tso = 1;
if (dst) {
@ -1193,7 +1199,7 @@ static inline int tcp_nagle_test(struct tcp_sock *tp, struct sk_buff *skb,
/* Don't use the nagle rule for urgent data (or for the final FIN).
* Nagle can be ignored during F-RTO too (see RFC4138).
*/
if (tp->urg_mode || (tp->frto_counter == 2) ||
if (tcp_urg_mode(tp) || (tp->frto_counter == 2) ||
(TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN))
return 1;
@ -2358,6 +2364,7 @@ static void tcp_connect_init(struct sock *sk)
tcp_init_wl(tp, tp->write_seq, 0);
tp->snd_una = tp->write_seq;
tp->snd_sml = tp->write_seq;
tp->snd_up = tp->write_seq;
tp->rcv_nxt = 0;
tp->rcv_wup = 0;
tp->copied_seq = 0;
@ -2567,8 +2574,7 @@ int tcp_write_wakeup(struct sock *sk)
tcp_event_new_data_sent(sk, skb);
return err;
} else {
if (tp->urg_mode &&
between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF))
if (between(tp->snd_up, tp->snd_una + 1, tp->snd_una + 0xFFFF))
tcp_xmit_probe_skb(sk, 1);
return tcp_xmit_probe_skb(sk, 0);
}