parallel ng_pptp_rcvdata():
- Add a per-node mutex.
- Acquire mutex during all ng_pptp_rcvdata() method.
- Make callouts protected by mutex. Now callouts count as
netgraph writers, but there are plans to allow reader callouts
for nodes, that have internal locking.
- Acquire mutex in ng_pptp_reset(), which can be triggered
by a message or node shutdown.
PR: kern/80035
Tested by: Deomid Ryabkov <myself rojer.pp.ru>
Reviewed by: Deomid Ryabkov <myself rojer.pp.ru>
d066ce1d4b