Skip to content

Commit

Permalink
Merge branch 'tcp-take-better-care-of-tw_substate-and-tw_rcv_nxt'
Browse files Browse the repository at this point in the history 
Eric Dumazet says:

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

While reviewing Jason Xing recent commit (0d9e5df "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: Jakub Kicinski <kuba@kernel.org>
  • Loading branch information
Jakub Kicinski committed Aug 29, 2024
2 parents 0fa5e94 + c0a1149 commit 59a0ad4
Show file tree
Hide file tree
Showing 5 changed files with 26 additions and 22 deletions.
2 changes: 1 addition & 1 deletion include/net/inet_timewait_sock.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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. */
Expand Down
4 changes: 2 additions & 2 deletions net/ipv4/inet_diag.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down Expand Up @@ -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 &&
Expand Down
6 changes: 3 additions & 3 deletions net/ipv4/tcp_ipv4.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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) {
Expand Down Expand Up @@ -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),
Expand Down Expand Up @@ -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);
}
Expand Down
31 changes: 17 additions & 14 deletions net/ipv4/tcp_minisocks.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
}

/*
Expand Down Expand Up @@ -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;

Expand All @@ -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;
Expand All @@ -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,
Expand Down Expand Up @@ -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. */

Expand Down Expand Up @@ -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;
Expand Down
5 changes: 3 additions & 2 deletions net/ipv6/tcp_ipv6.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down Expand Up @@ -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);
}
Expand Down

0 comments on commit 59a0ad4

Please sign in to comment.