K 10
svn:author
V 3
mjg
K 8
svn:date
V 27
2020-11-16T03:09:18.743949Z
K 7
svn:log
V 316
select: replace reference counting with memory barriers in selfd

Refcounting was added to combat a race between selfdfree and doselwakup,
but it adds avoidable overhead.

selfdfree detects it can free the object by ->sf_si == NULL, thus we can
ensure that the condition only holds after all accesses are completed.

END