net: openvswitch: ovs_ct_exit to be done under ovs_lock

[ Upstream commit 27de77cec985233bdf6546437b9761853265c505 ]

syzbot wrote:
| =============================
| WARNING: suspicious RCU usage
| 5.7.0-rc1+ #45 Not tainted
| -----------------------------
| net/openvswitch/conntrack.c:1898 RCU-list traversed in non-reader section!!
|
| other info that might help us debug this:
| rcu_scheduler_active = 2, debug_locks = 1
| ...
|
| stack backtrace:
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014
| Workqueue: netns cleanup_net
| Call Trace:
| ...
| ovs_ct_exit
| ovs_exit_net
| ops_exit_list.isra.7
| cleanup_net
| process_one_work
| worker_thread

To avoid that warning, invoke the ovs_ct_exit under ovs_lock and add
lockdep_ovsl_is_held as optional lockdep expression.

Link: https://lore.kernel.org/lkml/000000000000e642a905a0cbee6e@google.com


Fixes: 11efd5cb ("openvswitch: Support conntrack zone limit")
Cc: Pravin B Shelar <pshelar@ovn.org>
Cc: Yi-Hung Wei <yihung.wei@gmail.com>
Reported-by:  <syzbot+7ef50afd3a211f879112@syzkaller.appspotmail.com>
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 5ea7b72d4fac ("net: openvswitch: Fix Use-After-Free in ovs_ct_exit")
Signed-off-by: Sasha Levin <sashal@kernel.org>