Re: Internal vs. external barriers (was: Re: Interesting LKMM litmus test)

Boqun Feng
2023-01-18T17:00:26Z

On Wed, Jan 18, 2023 at 11:03:35AM -0500, Alan Stern wrote:
> On Tue, Jan 17, 2023 at 09:17:04PM -0800, Paul E. McKenney wrote:
> > On Tue, Jan 17, 2023 at 09:15:15PM -0500, Alan Stern wrote:
> > > Maybe we don't. Please test the patch below; I think it will do what
> > > you want -- and it doesn't rule out nesting.
> >
> > It works like a champ on manual/kernel/C-srcu*.litmus in the litmus
> > repository on github, good show and thank you!!!
> >
> > I will make more tests, and am checking this against the rest of the
> > litmus tests in the repo, but in the meantime would you be willing to
> > have me add your Signed-off-by?
>
> I'll email a real patch submission in the not-too-distant future,
> assuming you don't find any problems with the new code.

I haven't tested the following, but I think we also need it to avoid
(although rare) mixing srcu_struct with normal memory access?

Since you are working on a patch, I think I better mention this ;-)

Regards,
Boqun

diff --git a/tools/memory-model/lock.cat b/tools/memory-model/lock.cat
index 6b52f365d73a..c134c2027224 100644
--- a/tools/memory-model/lock.cat
+++ b/tools/memory-model/lock.cat
@@ -37,7 +37,7 @@ let RU = try RU with emptyset
let LF = LF | RL

(* There should be no ordinary R or W accesses to spinlocks *)
-let ALL-LOCKS = LKR | LKW | UL | LF | RU
+let ALL-LOCKS = LKR | LKW | UL | LF | RU | Srcu-lock | Srcu-unlock
flag ~empty [M \ IW] ; loc ; [ALL-LOCKS] as mixed-lock-accesses

(* Link Lock-Reads to their RMW-partner Lock-Writes *)

>
> Alan