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[Bug translator/17749] New: stap doesn't recognize "++" as a use
- From: "tromey at sourceware dot org" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sourceware dot org
- Date: Mon, 22 Dec 2014 21:12:22 +0000
- Subject: [Bug translator/17749] New: stap doesn't recognize "++" as a use
- Auto-submitted: auto-generated
https://sourceware.org/bugzilla/show_bug.cgi?id=17749
Bug ID: 17749
Summary: stap doesn't recognize "++" as a use
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: translator
Assignee: systemtap at sourceware dot org
Reporter: tromey at sourceware dot org
Consider this script:
global found = 0;
global found_pid = -1;
global sigstop = 19;
probe kernel.trace("signal_deliver") {
if (pid() == found_pid && $sig == sigstop) {
printf("%d\n", pid());
exit();
}
}
probe kernel.trace("sched_process_exec") {
if (execname() =~ @1 && ++found == 1) {
found_pid = pid();
raise(sigstop);
}
}
I ran it like so:
pokyo. sudo stap -g preattach.stp '.*ls.*'
29505
found=0x1
It printed out "found=0x1", but I think it should not have.
On irc jlebon pointed out:
<jlebon> normally stap prints written-to but never read-from globals at
shutdown
<jlebon> I think it doesn't see that it is being read
I modified the script, on his suggestion, to hoist the ++found out of
the condition. This suppressed the extraneous output.
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