Commit 59a0ad4f authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'tcp-take-better-care-of-tw_substate-and-tw_rcv_nxt' 

Eric Dumazet says:

====================
tcp: take better care of tw_substate and tw_rcv_nxt

While reviewing Jason Xing recent commit (0d9e5df4 "tcp: avoid reusing
FIN_WAIT2 when trying to find port in connect() process") I saw
we could remove the volatile qualifier for tw_substate field,
and I also added missing data-race annotations around tcptw->tw_rcv_nxt.
====================

Link: https://patch.msgid.link/20240827015250.3509197-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents 0fa5e94a c0a11493

include/net/inet_timewait_sock.h

+1 −1
Original line number Diff line number Diff line
@@ -58,7 +58,7 @@ struct inet_timewait_sock { 
#define tw_dr			__tw_common.skc_tw_dr



	__u32			tw_mark;

	volatile unsigned char	tw_substate;

	unsigned char		tw_substate;

	unsigned char		tw_rcv_wscale;



	/* Socket demultiplex comparisons on incoming packets. */

net/ipv4/inet_diag.c

+2 −2
Original line number Diff line number Diff line
@@ -442,7 +442,7 @@ static int inet_twsk_diag_fill(struct sock *sk, 
	inet_diag_msg_common_fill(r, sk);

	r->idiag_retrans      = 0;



	r->idiag_state	      = tw->tw_substate;

	r->idiag_state	      = READ_ONCE(tw->tw_substate);

	r->idiag_timer	      = 3;

	tmo = tw->tw_timer.expires - jiffies;

	r->idiag_expires      = jiffies_delta_to_msecs(tmo);
@@ -1209,7 +1209,7 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb, 
			if (num < s_num)

				goto next_normal;

			state = (sk->sk_state == TCP_TIME_WAIT) ?

				inet_twsk(sk)->tw_substate : sk->sk_state;

				READ_ONCE(inet_twsk(sk)->tw_substate) : sk->sk_state;

			if (!(idiag_states & (1 << state)))

				goto next_normal;

			if (r->sdiag_family != AF_UNSPEC &&

net/ipv4/tcp_ipv4.c

+3 −3
Original line number Diff line number Diff line
@@ -120,7 +120,7 @@ int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp) 
	struct tcp_sock *tp = tcp_sk(sk);

	int ts_recent_stamp;



	if (tw->tw_substate == TCP_FIN_WAIT2)

	if (READ_ONCE(tw->tw_substate) == TCP_FIN_WAIT2)

		reuse = 0;



	if (reuse == 2) {
@@ -1073,7 +1073,7 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb) 
	}



	tcp_v4_send_ack(sk, skb,

			tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,

			tcptw->tw_snd_nxt, READ_ONCE(tcptw->tw_rcv_nxt),

			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,

			tcp_tw_tsval(tcptw),

			READ_ONCE(tcptw->tw_ts_recent),
@@ -2948,7 +2948,7 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw, 


	seq_printf(f, "%4d: %08X:%04X %08X:%04X"

		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK",

		i, src, srcp, dest, destp, tw->tw_substate, 0, 0,

		i, src, srcp, dest, destp, READ_ONCE(tw->tw_substate), 0, 0,

		3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,

		refcount_read(&tw->tw_refcnt), tw);

}

net/ipv4/tcp_minisocks.c

+17 −14
Original line number Diff line number Diff line
@@ -52,16 +52,17 @@ tcp_timewait_check_oow_rate_limit(struct inet_timewait_sock *tw, 
	return TCP_TW_SUCCESS;

}



static void twsk_rcv_nxt_update(struct tcp_timewait_sock *tcptw, u32 seq)

static void twsk_rcv_nxt_update(struct tcp_timewait_sock *tcptw, u32 seq,

				u32 rcv_nxt)

{

#ifdef CONFIG_TCP_AO

	struct tcp_ao_info *ao;



	ao = rcu_dereference(tcptw->ao_info);

	if (unlikely(ao && seq < tcptw->tw_rcv_nxt))

	if (unlikely(ao && seq < rcv_nxt))

		WRITE_ONCE(ao->rcv_sne, ao->rcv_sne + 1);

#endif

	tcptw->tw_rcv_nxt = seq;

	WRITE_ONCE(tcptw->tw_rcv_nxt, seq);

}



/*
@@ -98,8 +99,9 @@ enum tcp_tw_status 
tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,

			   const struct tcphdr *th, u32 *tw_isn)

{

	struct tcp_options_received tmp_opt;

	struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);

	u32 rcv_nxt = READ_ONCE(tcptw->tw_rcv_nxt);

	struct tcp_options_received tmp_opt;

	bool paws_reject = false;

	int ts_recent_stamp;
@@ -117,26 +119,26 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, 
		}

	}



	if (tw->tw_substate == TCP_FIN_WAIT2) {

	if (READ_ONCE(tw->tw_substate) == TCP_FIN_WAIT2) {

		/* Just repeat all the checks of tcp_rcv_state_process() */



		/* Out of window, send ACK */

		if (paws_reject ||

		    !tcp_in_window(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq,

				   tcptw->tw_rcv_nxt,

				   tcptw->tw_rcv_nxt + tcptw->tw_rcv_wnd))

				   rcv_nxt,

				   rcv_nxt + tcptw->tw_rcv_wnd))

			return tcp_timewait_check_oow_rate_limit(

				tw, skb, LINUX_MIB_TCPACKSKIPPEDFINWAIT2);



		if (th->rst)

			goto kill;



		if (th->syn && !before(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt))

		if (th->syn && !before(TCP_SKB_CB(skb)->seq, rcv_nxt))

			return TCP_TW_RST;



		/* Dup ACK? */

		if (!th->ack ||

		    !after(TCP_SKB_CB(skb)->end_seq, tcptw->tw_rcv_nxt) ||

		    !after(TCP_SKB_CB(skb)->end_seq, rcv_nxt) ||

		    TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) {

			inet_twsk_put(tw);

			return TCP_TW_SUCCESS;
@@ -146,12 +148,13 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, 
		 * reset.

		 */

		if (!th->fin ||

		    TCP_SKB_CB(skb)->end_seq != tcptw->tw_rcv_nxt + 1)

		    TCP_SKB_CB(skb)->end_seq != rcv_nxt + 1)

			return TCP_TW_RST;



		/* FIN arrived, enter true time-wait state. */

		tw->tw_substate	  = TCP_TIME_WAIT;

		twsk_rcv_nxt_update(tcptw, TCP_SKB_CB(skb)->end_seq);

		WRITE_ONCE(tw->tw_substate, TCP_TIME_WAIT);

		twsk_rcv_nxt_update(tcptw, TCP_SKB_CB(skb)->end_seq,

				    rcv_nxt);



		if (tmp_opt.saw_tstamp) {

			WRITE_ONCE(tcptw->tw_ts_recent_stamp,
@@ -182,7 +185,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, 
	 */



	if (!paws_reject &&

	    (TCP_SKB_CB(skb)->seq == tcptw->tw_rcv_nxt &&

	    (TCP_SKB_CB(skb)->seq == rcv_nxt &&

	     (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq || th->rst))) {

		/* In window segment, it may be only reset or bare ack. */
@@ -229,7 +232,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, 
	 */



	if (th->syn && !th->rst && !th->ack && !paws_reject &&

	    (after(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt) ||

	    (after(TCP_SKB_CB(skb)->seq, rcv_nxt) ||

	     (tmp_opt.saw_tstamp &&

	      (s32)(READ_ONCE(tcptw->tw_ts_recent) - tmp_opt.rcv_tsval) < 0))) {

		u32 isn = tcptw->tw_snd_nxt + 65535 + 2;

net/ipv6/tcp_ipv6.c

+3 −2
Original line number Diff line number Diff line
@@ -1193,7 +1193,8 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb) 
#endif

	}



	tcp_v6_send_ack(sk, skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,

	tcp_v6_send_ack(sk, skb, tcptw->tw_snd_nxt,

			READ_ONCE(tcptw->tw_rcv_nxt),

			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,

			tcp_tw_tsval(tcptw),

			READ_ONCE(tcptw->tw_ts_recent), tw->tw_bound_dev_if,
@@ -2258,7 +2259,7 @@ static void get_timewait6_sock(struct seq_file *seq, 
		   src->s6_addr32[2], src->s6_addr32[3], srcp,

		   dest->s6_addr32[0], dest->s6_addr32[1],

		   dest->s6_addr32[2], dest->s6_addr32[3], destp,

		   tw->tw_substate, 0, 0,

		   READ_ONCE(tw->tw_substate), 0, 0,

		   3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,

		   refcount_read(&tw->tw_refcnt), tw);

}