Eric Dumazet says:
====================
net: block BH in TCP callbacks
Four layers using TCP stack were assuming sk_callback_lock could
be locked using read_lock() in their handlers because TCP stack
was running with BH disabled.
This is no longer the case. Since presumably the rest could
also depend on BH being disabled, just use read_lock_bh().
Then each layer might consider switching to RCU protection
and no longer depend on BH.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>