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SubjectRe: [PATCH] Use term cumul-fence instead of fence in ->prop ordering example
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@google.com
>
> Suggested-by: Alan Stern <stern@rowland.harvard.edu>
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> ---
> 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@rowland.harvard.edu>

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