On Mon, Aug 13, 2018 at 3:53 PM David Miller <da...@davemloft.net> wrote: > > From: Cong Wang <xiyou.wangc...@gmail.com> > Date: Mon, 13 Aug 2018 12:16:52 -0700 > > > Your fix doesn't make sense, because what ife_mod_lock protects > > is absolutely not touched in BH context, they have no race. > > It does make sense, the problem is if you acquire ife_mod_lock and > take a software interrupt while you hold it. > > If that software interrupt takes the tcfa_lock, we're setup for an > AB-BA deadlock.
The lockdep does make sense, for sure. The fix does NOT. > > And there is also no easy way to reverse the lock ordering to > avoid this either. There is. > > I therefore think his fix is perfectly fine and that's why I > applied it. I will send a revert and a better fix. Thanks.
