This warning is caused by the lock held by sctp_getsockopt() is on one
socket, while the other lock that sctp_close() is getting later is on
the newly created (which failed) socket during peeloff operation.
This patch is to avoid this warning by use lock_sock with subclass
SINGLE_DEPTH_NESTING as Wang Cong and Marcelo's suggestion.
Reported-by: Dmitry Vyukov <dvyukov@google.com> Suggested-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Suggested-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Xin Long <lucien.xin@gmail.com> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>