Date: Sun, 2 Mar 2003 14:27:45 -0800 (PST) From: Joel Ray Holveck <joelh@piqnet.org> To: FreeBSD-gnats-submit@FreeBSD.org Subject: ports/48852: sysutils/pstree can go into infinite loop for zombies [PATCH] Message-ID: <200303022227.h22MRjYU061341@thor.piqnet.org>
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>Number: 48852
>Category: ports
>Synopsis: sysutils/pstree can go into infinite loop for zombies [PATCH]
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-ports-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sun Mar 02 14:30:04 PST 2003
>Closed-Date:
>Last-Modified:
>Originator: Joel Ray Holveck
>Release: FreeBSD 5.0-RELEASE i386
>Organization:
>Environment:
System: FreeBSD thor.piqnet.org 5.0-RELEASE FreeBSD 5.0-RELEASE #13: Sun Feb 9 17:11:33 PST 2003 root@thor.piqnet.org:/usr/local/src/freebsd/src/sys/i386/compile/THOR i386
pstree v2.17
>Description:
Under FreeBSD 5.0, zombie processes are reported by ps with pid 0.
Also, init and swapper have ppid 0. This leads to a cycle, and pstree
is only designed to handle trees.
>How-To-Repeat:
thor$ perl -e 'fork() && sleep 100;'
^Z
[1]+ Stopped perl -e 'fork() && sleep 100;'
thor$ bg
[1]+ perl -e 'fork() && sleep 100;' &
thor$ ps ax | grep perl
0 p9 ZW 0:00.00 (perl)
33322 p9 S 0:00.02 perl -e fork() && sleep 100;
33374 p9 S+ 0:00.01 grep perl
Note the zombie perl with pid 0.
Now:
thor$ pstree|more
Watch the output for cycles. You can search for '00000' to find them easily.
>Fix:
I know that there's a patch mechanism in ports, but I'm not sure what
the proper way to submit a patch for that is. So here's a patch to
the pstree source.
--- pstree.c.~1~ Mon Dec 17 04:18:02 2001
+++ pstree.c Sun Mar 2 14:15:11 2003
@@ -655,8 +655,9 @@
sprintf(nhead, "%s%s ", head,
head[0] == '\0' ? "" : EXIST(P[idx].sister) ? C->bar : " ");
- for (child = P[idx].child; EXIST(child); child = P[child].sister)
- PrintTree(child, nhead);
+ if (P[idx].pid)
+ for (child = P[idx].child; EXIST(child); child = P[child].sister)
+ PrintTree(child, nhead);
}
void Usage(void) {
>Release-Note:
>Audit-Trail:
>Unformatted:
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