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SubjectRe: [PATCH RFC tools/lkmm 10/12] tools/memory-model: Add a S lock-based external-view litmus test
On Wed, Feb 21, 2018 at 01:38:35PM -0500, Alan Stern wrote:
> On Wed, 21 Feb 2018, Paul E. McKenney wrote:
>
> > On Wed, Feb 21, 2018 at 11:50:31AM -0500, Alan Stern wrote:
> > > On Wed, 21 Feb 2018, Paul E. McKenney wrote:
> > >
> > > > On Wed, Feb 21, 2018 at 10:09:00AM -0500, Alan Stern wrote:
> > > > > On Tue, 20 Feb 2018, Paul E. McKenney wrote:
> > > > >
> > > > > > From: Alan Stern <stern@rowland.harvard.edu>
> > > > > >
> > > > > > This commit adds a litmus test in which P0() and P1() form a lock-based S
> > > > > > litmus test, with the addition of P2(), which observes P0()'s and P1()'s
> > > > >
> > > > > Why do you call this an "S" litmus test? Isn't ISA2 a better
> > > > > description?
> > > >
> > > > Indeed, the name of the test is in fact ISA2.
> > >
> > > Sure; and the Changelog entry should reflect this.
> >
> > No argument.
>
> > ------------------------------------------------------------------------
> >
> > commit e6658d1d7fcc6391f3d00beaadc484243123a893
> > Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> > Date: Wed Feb 21 09:49:01 2018 -0800
> >
> > tools/memory-order: Add documentation of new litmus test
> >
> > The litmus-tests/README file lacked any mention of then litmus test
>
> s/lacked/lacks/
> s/then/the new/
>
> > named ISA2+pooncelock+pooncelock+pombonce.litmus. This commit therefore
>
> s/named //
>
> > adds this test.
>
> It adds a description of the test, not the test itself.

Good catches, fixed.

> > Reported-by: Alan Stern <stern@rowland.harvard.edu>
> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> >
> > diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README
> > index dca7d823ad57..aff3eb90e067 100644
> > --- a/tools/memory-model/litmus-tests/README
> > +++ b/tools/memory-model/litmus-tests/README
> > @@ -32,6 +32,11 @@ IRIW+poonceonces+OnceOnce.litmus
> > order of a pair of writes, where each write is to a different
> > variable by a different process?
> >
> > +ISA2+pooncelock+pooncelock+pombonce.litmus
> > + Tests whether the ordering provided by a lock-protected S litmus
>
> Call it an ISA2 litmus test, not an S litmus test!

Given the structure of the test, the relationship to S is important
because it helps motivate why anyone might care. But yes, having ISA2
only in the filename is a bit obtuse. How about the following?

ISA2+pooncelock+pooncelock+pombonce.litmus
Tests whether the ordering provided by a lock-protected S
litmus test is visible to an external process whose accesses are
separated by smp_mb(). This addition of an external process to
S is otherwise known as ISA2.

Thanx, Paul

> > + test is visible to an external process whose accesses are
> > + separated by smp_mb().
> > +
> > ISA2+poonceonces.litmus
> > As below, but with store-release replaced with WRITE_ONCE()
> > and load-acquire replaced with READ_ONCE().
>
> Alan
>

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