On Mon, Aug 31, 2020 at 11:20:36AM -0700, paulmck@xxxxxxxxxx wrote: > From: "Paul E. McKenney" <paulmck@xxxxxxxxxx> > > The Linux kernel has a number of categories of ordering primitives, which > are recorded in the LKMM implementation and hinted at by cheatsheet.txt. > But there is no overview of these categories, and such an overview > is needed in order to understand multithreaded LKMM litmus tests. > This commit therefore adds an ordering.txt as well as extracting a > control-dependencies.txt from memory-barriers.txt. It also updates the > README file. > > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> > --- This document could use some careful editing. But one pair of errors stands out in particular: > diff --git a/tools/memory-model/Documentation/ordering.txt b/tools/memory-model/Documentation/ordering.txt > new file mode 100644 > index 0000000..4b2cc55 > --- /dev/null > +++ b/tools/memory-model/Documentation/ordering.txt > +2. Ordered memory accesses. These operations order themselves > + against some or all of the CPUs prior or subsequent accesses, > + depending on the category of operation. > + > + a. Release operations. This category includes > + smp_store_release(), atomic_set_release(), > + rcu_assign_pointer(), and value-returning RMW operations > + whose names end in _release. These operations order > + their own store against all of the CPU's subsequent ---------------------------------------------------------^^^^^^^^^^ > + memory accesses. > + > + b. Acquire operations. This category includes > + smp_load_acquire(), atomic_read_acquire(), and > + value-returning RMW operations whose names end in > + _acquire. These operations order their own load against > + all of the CPU's prior memory accesses. ---------------------------------^^^^^ Double-oops! Alan
