CVS commit: src/sys

["Ryota Ozaki" <ozaki-r%netbsd.org@localhost>]

Module Name:    src
Committed By:   ozaki-r
Date:           Fri Nov 17 09:26:36 UTC 2017

Modified Files:
        src/sys/kern: subr_localcount.c
        src/sys/sys: localcount.h

Log Message:
Implement a debugging facility (overflow/underflow detection) for localcount

We cannot get an accurate count from a localcount instance because it consists
of per-cpu counters and we have no way to sum them up atomically. So we cannot
detect counter overflow/underflow as we can do on a normal refcount.

The facility adds an atomic counter to each localcount instance to enable the
validations. The counter ups and downs in synchronization with the per-CPU
counters. The counter is used iff both DEBUG and LOCKDEBUG are enabled in the
kernel.

Discussed on tech-kern@


To generate a diff of this commit:
cvs rdiff -u -r1.6 -r1.7 src/sys/kern/subr_localcount.c
cvs rdiff -u -r1.4 -r1.5 src/sys/sys/localcount.h

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