CVS commit: src

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sun Dec  1 15:28:20 UTC 2019

Modified Files:
        src/sys/sys: pslist.h
        src/tests/include/sys: t_pslist.c

Log Message:
Adapt <sys/pslist.h> to use atomic_load/store_*.

Changes:

- membar_producer();
  *p = v;

    =>

  atomic_store_release(p, v);

  (Effectively like using membar_exit instead of membar_producer,
  which is what we should have been doing all along so that stores by
  the `reader' can't affect earlier loads by the writer, such as
  KASSERT(p->refcnt == 0) in the writer and atomic_inc(&p->refcnt) in
  the reader.)

- p = *pp;
  if (p != NULL) membar_datadep_consumer();

    =>

  p = atomic_load_consume(pp);

  (Only makes a difference on DEC Alpha.  As long as lists generally
  have at least one element, this is not likely to make a big
  difference, and keeps the code simpler and clearer.)

No other functional change intended.  While here, annotate each
synchronizing load and store with its counterpart in a comment.


To generate a diff of this commit:
cvs rdiff -u -r1.6 -r1.7 src/sys/sys/pslist.h
cvs rdiff -u -r1.1 -r1.2 src/tests/include/sys/t_pslist.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.