On Thu, Nov 05, 2020 at 02:00:14PM -0800, paulmck@xxxxxxxxxx wrote: > From: "Paul E. McKenney" <paulmck@xxxxxxxxxx> > > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> > --- > tools/memory-model/Documentation/glossary.txt | 155 ++++++++++++++++++++++++++ > 1 file changed, 155 insertions(+) > create mode 100644 tools/memory-model/Documentation/glossary.txt > > diff --git a/tools/memory-model/Documentation/glossary.txt b/tools/memory-model/Documentation/glossary.txt > new file mode 100644 > index 0000000..036fa28 > --- /dev/null > +++ b/tools/memory-model/Documentation/glossary.txt > @@ -0,0 +1,155 @@ > +This document contains brief definitions of LKMM-related terms. Like most > +glossaries, it is not intended to be read front to back (except perhaps > +as a way of confirming a diagnosis of OCD), but rather to be searched > +for specific terms. > + > + > +Address Dependency: When the address of a later memory access is computed > + based on the value returned by an earlier load, an "address > + dependency" extends from that load extending to the later access. > + Address dependencies are quite common in RCU read-side critical > + sections: > + > + 1 rcu_read_lock(); > + 2 p = rcu_dereference(gp); > + 3 do_something(p->a); > + 4 rcu_read_unlock(); > + > + In this case, because the address of "p->a" on line 3 is computed > + from the value returned by the rcu_dereference() on line 2, the > + address dependency extends from that rcu_dereference() to that > + "p->a". In rare cases, optimizing compilers can destroy address > + dependencies. Please see Documentation/RCU/rcu_dereference.txt > + for more information. > + > + See also "Control Dependency". > + > +Acquire: With respect to a lock, acquiring that lock, for example, > + using spin_lock(). With respect to a non-lock shared variable, > + a special operation that includes a load and which orders that > + load before later memory references running on that same CPU. > + An example special acquire operation is smp_load_acquire(), > + but atomic_read_acquire() and atomic_xchg_acquire() also include > + acquire loads. > + > + When an acquire load returns the value stored by a release store > + to that same variable, then all operations preceding that store Change this to: When an acquire load reads-from a release store , and put a reference to "Reads-from"? I think this makes the document more consistent in that it makes clear "an acquire load returns the value stored by a release store to the same variable" is not a special case, it's simple a "Reads-from". > + happen before any operations following that load acquire. Add a reference to the definition of "happen before" in explanation.txt? Regards, Boqun > + > + See also "Relaxed" and "Release". > + [...]
