On Mon, Aug 31, 2020 at 09:23:09PM -0400, Alan Stern wrote: > 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! Hey, at least I am consistently wrong! ;-) Fixed, thank you! Thanx, Paul
