CVS commit: [prg-localcount2] src/sys/kern

["Paul Goyette" <pgoyette%netbsd.org@localhost>]

Module Name:    src
Committed By:   pgoyette
Date:           Fri May 12 22:12:23 UTC 2017

Modified Files:
        src/sys/kern [prg-localcount2]: subr_localcount.c

Log Message:
When we're draining the localcount's references, transfer the local
CPU's reference count to the global total, and then zero it.  Any
further calls to localcount_release() will adjust only the global
counter.

Avoids a race condition which depends on having localcount_release()
being aware of whether the local CPU's contribution has already been
accounted for.  Thanks to Kengo NAKAHARA for bringing up the question,
and to riastradh@ for the solution.


To generate a diff of this commit:
cvs rdiff -u -r1.1.6.4 -r1.1.6.5 src/sys/kern/subr_localcount.c

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