On Wed, 6 Mar 2024 10:09:48 -0800 "Paul E. McKenney" <paulmck@xxxxxxxxxx> 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
