Date: Tue, 20 May 2003 19:46:11 +0200 (CEST) From: Jilles Tjoelker <jilles@stack.nl> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/52490: ^T'ing a zombie causes 'calcru: negative time' messages Message-ID: <20030520174611.4C53E1CC5D@turtle.stack.nl> Resent-Message-ID: <200305201750.h4KHo8wa094693@freefall.freebsd.org>
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>Number: 52490
>Category: kern
>Synopsis: ^T'ing a zombie causes 'calcru: negative time' messages
>Confidential: no
>Severity: serious
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Tue May 20 10:50:08 PDT 2003
>Closed-Date:
>Last-Modified:
>Originator: Jilles Tjoelker
>Release: FreeBSD 5.1-BETA i386
>Organization:
>Environment:
System: FreeBSD turtle.stack.nl 5.1-BETA FreeBSD 5.1-BETA #10: Mon May 12 15:30:54 CEST 2003 jilles@turtle.stack.nl:/usr/obj/usr/src/sys/TURTLE i386
It occurs on 4.8-RELEASE and many older 4.x versions as well.
>Description:
When ^T'ing (ttyinfo) a zombie, calcru() is called and logs a 'negative time'
message. To achieve this, only zombies must be in the foreground process group
of the terminal.
>How-To-Repeat:
Compile and run the negtime program. Pressing ^T after it has printed the
message 'done' causes a log message 'calcru: negative time...'. (It may be
necessary to do stty status ^t beforehand.)
>Fix:
A patch (against 4-STABLE) is attached which prevents calcru() from being
called on zombies from ttyinfo(). I don't know in what process states calcru()
may be called exactly, but for the rest of /sys/kern it's only used for
accounting, exiting and getrusage() and therefore cannot be called on zombies.
(Perhaps this is or should be documented somewhere.)
--- negtime.c begins here ---
/* Copyright (C) 2001 by Jilles Tjoelker */
#include <sys/types.h>
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
int
main(int argc, char *argv[])
{
int pid,pgid;
if (argc != 1)
{
fprintf(stderr, "Usage: %s\n", argv[0]);
return(1);
}
switch (pid=fork())
{
case 0:
signal(SIGTTOU,SIG_IGN);
pid=getpid();
pgid=getpgrp();
if (setpgid(pid,pid)==-1)
{
perror("Error in setpgid()");
_exit(1);
}
if (tcsetpgrp(0,pid)==-1)
{
setpgid(pid,pgid);
perror("Error in tcsetpgrp()");
_exit(2);
}
sleep(1);
printf("done\n");
_exit(127);
break;
case -1:
fprintf(stderr, "Error in fork().\n");
break;
default:
sleep(10);
}
return 0;
}
/* vim:ts=8:cin:sw=4:kp=man\ -S3\:2\:9\:1\:4\:5\:6\:7\:8\:n
*/
--- negtime.c ends here ---
--- ttyinfo_zombie.patch begins here ---
--- /usr/src/sys/kern/tty.c.orig Mon Mar 11 02:32:31 2002
+++ /usr/src/sys/kern/tty.c Sun Jan 19 21:40:16 2003
@@ -2323,7 +2323,7 @@
pick->p_stat == SRUN ? "running" :
pick->p_wmesg ? pick->p_wmesg : "iowait");
- if (pick->p_flag & P_INMEM) {
+ if (pick->p_flag & P_INMEM && pick->p_stat != SZOMB) {
calcru(pick, &utime, &stime, NULL);
/* Print user time. */
--- ttyinfo_zombie.patch ends here ---
>Release-Note:
>Audit-Trail:
>Unformatted:
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