On Mon, Jul 29, 2019 at 04:41:34PM -0400, Alan Stern wrote: > On Mon, 29 Jul 2019, Joel Fernandes (Google) wrote: > > > To reduce ambiguity in the more exotic ->prop ordering example, let us > > use the term cumul-fence instead fence for the 2 fences, so that the > > implict ->rfe on loads/stores to Y are covered by the description. > > > > Link: https://lore.kernel.org/lkml/20190729121745.GA140682@xxxxxxxxxx > > > > Suggested-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> > > --- > > tools/memory-model/Documentation/explanation.txt | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/tools/memory-model/Documentation/explanation.txt b/tools/memory-model/Documentation/explanation.txt > > index 68caa9a976d0..634dc6db26c4 100644 > > --- a/tools/memory-model/Documentation/explanation.txt > > +++ b/tools/memory-model/Documentation/explanation.txt > > @@ -1302,7 +1302,7 @@ followed by an arbitrary number of cumul-fence links, ending with an > > rfe link. You can concoct more exotic examples, containing more than > > one fence, although this quickly leads to diminishing returns in terms > > of complexity. For instance, here's an example containing a coe link > > -followed by two fences and an rfe link, utilizing the fact that > > +followed by two cumul-fences and an rfe link, utilizing the fact that > > release fences are A-cumulative: > > > > int x, y, z; > > @@ -1334,10 +1334,10 @@ If x = 2, r0 = 1, and r2 = 1 after this code runs then there is a prop > > link from P0's store to its load. This is because P0's store gets > > overwritten by P1's store since x = 2 at the end (a coe link), the > > smp_wmb() ensures that P1's store to x propagates to P2 before the > > -store to y does (the first fence), the store to y propagates to P2 > > +store to y does (the first cumul-fence), the store to y propagates to P2 > > before P2's load and store execute, P2's smp_store_release() > > guarantees that the stores to x and y both propagate to P0 before the > > -store to z does (the second fence), and P0's load executes after the > > +store to z does (the second cumul-fence), and P0's load executes after the > > store to z has propagated to P0 (an rfe link). > > > > In summary, the fact that the hb relation links memory access events > > Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Queued with Alan's ack, thank you both! Thanx, Paul
