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tcp: remove volatile qualifier on tw_substate

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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: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://patch.msgid.link/20240827015250.3509197-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-08-27 01:52:49 +00:00 committed by Jakub Kicinski
parent 0fa5e94a18
commit 3e5cbbb1fb
5 changed files with 8 additions and 8 deletions
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2
include/net/inet_timewait_sock.h
View File

@ -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. */

4
net/ipv4/inet_diag.c
View File

@ -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 &&

4
net/ipv4/tcp_ipv4.c
View File

@ -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);
}

4
net/ipv4/tcp_minisocks.c
View File

@ -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) {

2
net/ipv6/tcp_ipv6.c
View File

@ -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);
}