On Fri, Feb 03, 2023 at 08:19:13PM +0000, Joel Fernandes (Google) wrote: > During a code-reading exercise of linux-kernel.cat CAT file, I generated > a graph to show the to-r relations. While likely not problematic for the > model, I found it confusing that a read-write address dependency would > show as a to-r edge on the graph. > > This patch therefore restricts the to-r links derived from addr to only > read-read address dependencies, so that read-write address dependencies don't > show as to-r in the graphs. This should also prevent future users of to-r from > deriving incorrect relations. Note that a read-write address dep, obviously, > still ends up in the ppo relation via the to-w relation. > > I verified that a read-read address dependency still shows up as a to-r > link in the graph, as it did before. > > For reference, the problematic graph was generated with the following > command: > herd7 -conf linux-kernel.cfg \ > -doshow dep -doshow to-r -doshow to-w ./foo.litmus -show all -o OUT/ > > Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> > --- > tools/memory-model/linux-kernel.cat | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat > index d70315fddef6..26e6f0968143 100644 > --- a/tools/memory-model/linux-kernel.cat > +++ b/tools/memory-model/linux-kernel.cat > @@ -69,7 +69,7 @@ let dep = addr | data > let rwdep = (dep | ctrl) ; [W] > let overwrite = co | fr > let to-w = rwdep | (overwrite & int) | (addr ; [Plain] ; wmb) > -let to-r = addr | (dep ; [Marked] ; rfi) > +let to-r = (addr ; [R]) | (dep ; [Marked] ; rfi) > let ppo = to-r | to-w | fence | (po-unlock-lock-po & int) > > (* Propagation: Ordering from release operations and strong fences. *) > -- > 2.39.1.519.gcb327c4b5f-goog Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
