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tcp: Don't change unlocked socket state in tcp_v4_err().

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Alexey Kuznetsov noticed a regression introduced by
commit f1ecd5d9e7
("Revert Backoff [v3]: Revert RTO on ICMP destination unreachable")

The RTO and timer modification code added to tcp_v4_err()
doesn't check sock_owned_by_user(), which if true means we
don't have exclusive access to the socket and therefore cannot
modify it's critical state.

Just skip this new code block if sock_owned_by_user() is true
and eliminate the now superfluous sock_owned_by_user() code
block contained within.

Reported-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
CC: Damian Lukowski <damian@tvk.rwth-aachen.de>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
This commit is contained in:
David S. Miller 2010-11-12 13:35:00 -08:00
parent 5ef41308f9
commit 8f49c2703b
1 changed files with 3 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
net/ipv4/tcp_ipv4.c
View file

@ -415,6 +415,9 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
!icsk->icsk_backoff)
break;
if (sock_owned_by_user(sk))
break;
icsk->icsk_backoff--;
inet_csk(sk)->icsk_rto = __tcp_set_rto(tp) <<
icsk->icsk_backoff;
@ -429,11 +432,6 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
if (remaining) {
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
remaining, TCP_RTO_MAX);
} else if (sock_owned_by_user(sk)) {
/* RTO revert clocked out retransmission,
* but socket is locked. Will defer. */
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
HZ/20, TCP_RTO_MAX);
} else {
/* RTO revert clocked out retransmission.
* Will retransmit now */