Commit 33f5f57e authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
Browse files

tcp: kill pointless urg_mode 



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: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 654bed16

include/linux/tcp.h

+4 −5
Original line number Diff line number Diff line
@@ -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 */

net/ipv4/tcp.c

+1 −3
Original line number Diff line number Diff line
@@ -497,11 +497,9 @@ 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,

			    int nonagle)

net/ipv4/tcp_input.c

+6 −5
Original line number Diff line number Diff line
@@ -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);

net/ipv4/tcp_minisocks.c

+1 −0
Original line number Diff line number Diff line
@@ -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);

net/ipv4/tcp_output.c

+12 −6
Original line number Diff line number Diff line
@@ -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);

	}

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