linux-toradex.git/tools/memory-model, branch v5.11-rc6

tools/memory-model: Label MP tests' producers and consumers

2020-11-07T01:25:17+00:00

This commit adds comments that label the MP tests' producer and consumer
processes, and also that label the "exists" clause as the bad outcome.

Reported-by: Johannes Weiner 
Signed-off-by: Paul E. McKenney

tools/memory-model: Use "buf" and "flag" for message-passing tests

2020-11-07T01:25:16+00:00

The use of "x" and "y" for message-passing tests is fine for people
familiar with memory models and litmus-test nomenclature, but is a bit
obtuse for others.  This commit therefore substitutes "buf" for "x" and
"flag" for "y" for the MP tests.  There are a few special-case MP tests
that use locks and these are unchanged.  There is another MP test that
uses pointers, and this is changed to name the pointer "p".

Reported-by: Johannes Weiner 
Signed-off-by: Paul E. McKenney

tools/memory-model: Add types to litmus tests

2020-11-07T01:25:16+00:00

This commit adds type information for global variables in the litmus
tests in order to allow easier use with klitmus7.

Signed-off-by: Paul E. McKenney

tools/memory-model: Add a glossary of LKMM terms

2020-11-07T01:24:53+00:00

[ paulmck: Apply Alan Stern feedback. ]
Signed-off-by: Paul E. McKenney

tools/memory-model: Document categories of ordering primitives

2020-11-07T01:24:50+00:00

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.

[ paulmck:  Apply Akira Yokosawa file-placement feedback. ]
[ paulmck:  Apply Alan Stern feedback. ]
[ paulmck:  Apply self-review feedback. ]
Signed-off-by: Paul E. McKenney

tools/memory-model: Move Documentation description to Documentation/README

2020-10-26T23:18:53+00:00

This commit moves the descriptions of the files residing in
tools/memory-model/Documentation to a README file in that directory,
leaving behind the description of tools/memory-model/Documentation/README
itself.  After this change, tools/memory-model/Documentation/README
provides a guide to the files in the tools/memory-model/Documentation
directory, guiding people with different skills and needs to the most
appropriate starting point.

Signed-off-by: Paul E. McKenney

tools: memory-model: Document that the LKMM can easily miss control dependencies

2020-10-26T23:18:53+00:00

Add a small section to the litmus-tests.txt documentation file for
the Linux Kernel Memory Model explaining that the memory model often
fails to recognize certain control dependencies.

Suggested-by: Akira Yokosawa 
Signed-off-by: Alan Stern 
Reviewed-by: Joel Fernandes (Google) 
Signed-off-by: Paul E. McKenney

tools/memory-model: Expand the cheatsheet.txt notion of relaxed

2020-09-04T18:58:15+00:00

This commit adds a key entry enumerating the various types of relaxed
operations.  While in the area, it also renames the relaxed rows.

[ paulmck: Apply Boqun Feng feedback. ]
Acked-by: Boqun Feng 
Signed-off-by: Paul E. McKenney

tools/memory-model: Add a simple entry point document

2020-09-03T16:51:01+00:00

Current LKMM documentation assumes that the reader already understands
concurrency in the Linux kernel, which won't necessarily always be the
case.  This commit supplies a simple.txt file that provides a starting
point for someone who is new to concurrency in the Linux kernel.
That said, this file might also useful as a reminder to experienced
developers of simpler approaches to dealing with concurrency.

Link: Link: https://lwn.net/Articles/827180/
[ paulmck: Apply feedback from Joel Fernandes. ]
Co-developed-by: Dave Chinner 
Signed-off-by: Dave Chinner 
Co-developed-by: Paul E. McKenney 
Signed-off-by: Paul E. McKenney

tools/memory-model: Improve litmus-test documentation

2020-09-03T16:51:01+00:00

The current LKMM documentation says very little about litmus tests, and
worse yet directs people to the herd7 documentation for more information.
Now, the herd7 documentation is quite voluminous and educational,
but it is intended for people creating and modifying memory models,
not those attempting to use them.

This commit therefore updates README and creates a litmus-tests.txt
file that gives an overview of litmus-test format and describes ways of
modeling various special cases, illustrated with numerous examples.

[ paulmck: Add Alan Stern feedback. ]
[ paulmck: Apply Dave Chinner feedback. ]
[ paulmck: Apply Andrii Nakryiko feedback. ]
[ paulmck: Apply Johannes Weiner feedback. ]
Link: https://lwn.net/Articles/827180/
Reported-by: Dave Chinner 
Acked-by: Peter Zijlstra (Intel) 
Signed-off-by: Paul E. McKenney