On Wed, 6 Mar 2024 10:09:48 -0800
"Paul E. McKenney" <paul...@kernel.org> wrote:
> > Perhaps we need a way to annotate them, like we have with __rcu. "__shared"?
> >
> > Then all accesses to that variable must be wrapped with a READ_ONCE() or
> > WRITE_ONCE()? I mean, if this can cause legitimate bugs, we should probably
> > address it like we do with locking and RCU.
>
> If we want that, just mark the field "volatile", as in "jiffies".
I already know Linus's view on "volatile" variables ;-)
>
> And one of the strengths of READ_ONCE() and WRITE_ONCE() is that they
> allow non-volatile access where it is safe. For example, if you hold the
> lock protecting all stores to that variable, you still need WRITE_ONCE()
> but not READ_ONCE(). In initialization and cleanup code, you don't
> need either.
I guess the current static analyzers just look to see where READ_ONCE() or
WRITE_ONCE() is used and checks to see if other places have them properly
used. I'm guessing that's where the OP patch came from.
Sounds like we just need a ADD_ONCE() or INC_ONCE() then. Because I am not
taking a
WRITE_ONCE(a, READ_ONCE(a) + 1);
patch that replaces a simple "a++".
-- Steve
