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tcp: add tcp_done_with_error() helper

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[ Upstream commit 5e514f1cba090e1c8fff03e92a175eccfe46305f ]

tcp_reset() ends with a sequence that is carefuly ordered.

We need to fix [e]poll bugs in the following patches,
it makes sense to use a common helper.

Suggested-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Link: https://lore.kernel.org/r/20240528125253.1966136-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 853c3bd7b791 ("tcp: fix race in tcp_write_err()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eric Dumazet 2024-05-28 12:52:50 +00:00 committed by Greg Kroah-Hartman
parent 13829bfb38
commit ea734f7724
3 changed files with 23 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/tcp.h
View File

@ -677,6 +677,7 @@ void tcp_skb_collapse_tstamp(struct sk_buff *skb,
/* tcp_input.c */
void tcp_rearm_rto(struct sock *sk);
void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
void tcp_done_with_error(struct sock *sk, int err);
void tcp_reset(struct sock *sk, struct sk_buff *skb);
void tcp_fin(struct sock *sk);
void tcp_check_space(struct sock *sk);

2
net/ipv4/tcp.c
View File

@ -598,7 +598,7 @@ __poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
*/
mask |= EPOLLOUT | EPOLLWRNORM;
}
/* This barrier is coupled with smp_wmb() in tcp_reset() */
/* This barrier is coupled with smp_wmb() in tcp_done_with_error() */
smp_rmb();
if (READ_ONCE(sk->sk_err) ||
!skb_queue_empty_lockless(&sk->sk_error_queue))

32
net/ipv4/tcp_input.c
View File

@ -4469,9 +4469,26 @@ static enum skb_drop_reason tcp_sequence(const struct tcp_sock *tp,
return SKB_NOT_DROPPED_YET;
}
void tcp_done_with_error(struct sock *sk, int err)
{
/* This barrier is coupled with smp_rmb() in tcp_poll() */
WRITE_ONCE(sk->sk_err, err);
smp_wmb();
tcp_write_queue_purge(sk);
tcp_done(sk);
if (!sock_flag(sk, SOCK_DEAD))
sk_error_report(sk);
}
EXPORT_SYMBOL(tcp_done_with_error);
/* When we get a reset we do this. */
void tcp_reset(struct sock *sk, struct sk_buff *skb)
{
int err;
trace_tcp_receive_reset(sk);
/* mptcp can't tell us to ignore reset pkts,
@ -4483,24 +4500,17 @@ void tcp_reset(struct sock *sk, struct sk_buff *skb)
/* We want the right error as BSD sees it (and indeed as we do). */
switch (sk->sk_state) {
case TCP_SYN_SENT:
WRITE_ONCE(sk->sk_err, ECONNREFUSED);
err = ECONNREFUSED;
break;
case TCP_CLOSE_WAIT:
WRITE_ONCE(sk->sk_err, EPIPE);
err = EPIPE;
break;
case TCP_CLOSE:
return;
default:
WRITE_ONCE(sk->sk_err, ECONNRESET);
err = ECONNRESET;
}
/* This barrier is coupled with smp_rmb() in tcp_poll() */
smp_wmb();
tcp_write_queue_purge(sk);
tcp_done(sk);
if (!sock_flag(sk, SOCK_DEAD))
sk_error_report(sk);
tcp_done_with_error(sk, err);
}
/*