Commit 3e5cbbb1 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

tcp: remove volatile qualifier on tw_substate 



Using a volatile qualifier for a specific struct field is unusual.

Use instead READ_ONCE()/WRITE_ONCE() where necessary.

tcp_timewait_state_process() can change tw_substate while other
threads are reading this field.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarJason Xing <kerneljasonxing@gmail.com>
Link: https://patch.msgid.link/20240827015250.3509197-2-edumazet@google.com


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

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

+2 −2
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) {
@@ -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

+2 −2
Original line number Diff line number Diff line
@@ -117,7 +117,7 @@ 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 */
@@ -150,7 +150,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, 
			return TCP_TW_RST;



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

		tw->tw_substate	  = TCP_TIME_WAIT;

		WRITE_ONCE(tw->tw_substate, TCP_TIME_WAIT);

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



		if (tmp_opt.saw_tstamp) {

net/ipv6/tcp_ipv6.c

+1 −1
Original line number Diff line number Diff line
@@ -2258,7 +2258,7 @@ 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);

}