Simon Kirby reported lockdep warnings and following messages :

[104661.897577] huh, entered softirq 3 NET_RX ffffffff81613740
preempt_count 00000101, exited with 00000102?

[104661.923653] huh, entered softirq 3 NET_RX ffffffff81613740
preempt_count 00000101, exited with 00000102?

Problem comes from commit 0e734419
(ipv4: Use inet_csk_route_child_sock() in DCCP and TCP.)

If inet_csk_route_child_sock() returns NULL, we should release socket
lock before freeing it.

Another lock imbalance exists if __inet_inherit_port() returns an error
since commit 093d2823 ( tproxy: fix hash locking issue when using
port redirection in __inet_inherit_port()) a backport is also needed for
>= 2.6.37 kernels.
Reported-by: Simon Kirby <sim@hostway.ca>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Balazs Scheidler <bazsi@balabit.hu>
CC: KOVACS Krisztian <hidden@balabit.hu>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Simon Kirby <sim@hostway.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>