title: Watch a Variable Changing Value in a Thread
name: varwatch.stp
version: 1.0
author: anonymous
keywords: monitoring
subsystem: any
status: proposed
exit: user-controlled
output: trace
scope: system-wide
description: This script places a set of probes (specified by $1), each of which monitors the state of some context $variable expression (specified by $2).  Whenever the value changes, with respect to the active thread, the event is traced.
test_check: stap -wp4 varwatch.stp 'kernel.statement("do_sys_open@fs/open.c:*")' '$$vars'
test_installcheck: stap -w varwatch.stp 'kernel.statement("do_sys_open@fs/open.c:*")' '$$vars' -c "sleep 0.2"