From: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx> To reduce ambiguity in the more exotic ->prop ordering example, this commit uses the term cumul-fence instead of the term fence for the two 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> Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxx> --- 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 -- 2.17.1
