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

[Jonas Oberhauser]

On 1/20/2023 4:32 PM, Paul E. McKenney wrote:
> On Fri, Jan 20, 2023 at 01:51:01PM +0100, Jonas Oberhauser wrote:
> > I'm not going to get it right today, am I?
> Believe me, I know that feeling!  Open-source development is therefore
> an extremely good character-building exercise.  At least that is what
> I keep telling myself.  ;-)

"Calvin, go do something you hate! Being miserable builds character!"

> > +let srcu-rscs = ([Srcu-lock] ; (data ; [~ Srcu-unlock] ; rfe) * ; data ;
> > [Srcu-unlock]) & loc
> >
> > I see now that I copied the format from your message but without realizing
> > the original had a `|` where I have a `;`.
> > I hope this version is finally right and perhaps more natural than the (data
> > | rf) version, considering rf can't actually appear in most places and this
> > more closely matches carry-dep;data.
> > But of course feel free to use
> > +let srcu-rscs = ([Srcu-lock] ; (data  | [~ Srcu-unlock] ; rf)+ ;
> > [Srcu-unlock]) & loc
> > instead if you prefer.
>
> The reason for favoring "rf" over "rfe" is the possibility of a litmus
> test where the process containing the srcu_down_read() sometimes but
> not always also has the matching srcu_up_read().  Perhaps a pair of "if"
> statements control which process does the matching srcu_up_read().

If you put the redefinition of data early enough to affect this 
definition, the rfi option should be covered by the carry-dep in the 
redefinition of data, so I left it out.

> And thank you!!!

always ;-)

jonas