[PATCH] global: the _bh variety of rcu helpers have been unified

[Bruno Wolff III]

On Thu, Mar 14, 2019 at 23:14:39 -0600,
  "Jason A. Donenfeld" <Jason at zx2c4.com> wrote:
>---
>Hey Bruno,
>
>Based on your research, how does the below strike you? It's certainly
>not pretty, but I'm struggling to come up with a better solution.

I think anything that doesn't try to keep the _bh versions around is going to 
be ugly. But keeping the _bh versions is not going to be acceptible upstream, 
so that doesn't seem to be an option. What you did looks pretty good 
given the constraints.

In the talk I saw, the motivation for the change was that mismatching 
rcu functions caused security issues, though I don't know how practical 
it is to exploit those mistakes. So I worry a bit about breaking things 
in old kernels accidentally, in the future. I don't have any good ideas for 
automatically catching misuse in new code.

I did try the version you committed, yesterday, and it seemed to work 
fine on a 5.1 kernel.