Commit 8f49c270 authored Nov 12, 2010 by David S. Miller

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



Alexey Kuznetsov noticed a regression introduced by
commit f1ecd5d9
("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>

parent 5ef41308

net/ipv4/tcp_ipv4.c

+3 −5

Original line number	Diff line number	Diff line
		@@ -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 */

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