[src/trunk]: src/sys/kern Correct the rule to iterate over LWPs with PT_LWPNE...

[kamil <kamil%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/9978ec009be5
branches:  trunk
changeset: 466832:9978ec009be5
user:      kamil <kamil%NetBSD.org@localhost>
date:      Fri Jan 03 00:37:29 2020 +0000

description:
Correct the rule to iterate over LWPs with PT_LWPNEXT and PT_LWPINFO

Correctly exclude dead/dying/zombie and system threads.

Fixes kern/54802 (gdb -p kills the kernel) by <martin>

diffstat:

 sys/kern/sys_ptrace_common.c |  11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)

diffs (39 lines):

diff -r bfabb75392c4 -r 9978ec009be5 sys/kern/sys_ptrace_common.c
--- a/sys/kern/sys_ptrace_common.c      Thu Jan 02 23:51:48 2020 +0000
+++ b/sys/kern/sys_ptrace_common.c      Fri Jan 03 00:37:29 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_ptrace_common.c,v 1.76 2019/12/26 08:52:38 kamil Exp $     */
+/*     $NetBSD: sys_ptrace_common.c,v 1.77 2020/01/03 00:37:29 kamil Exp $     */
 
 /*-
  * Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -118,7 +118,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_ptrace_common.c,v 1.76 2019/12/26 08:52:38 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_ptrace_common.c,v 1.77 2020/01/03 00:37:29 kamil Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_ptrace.h"
@@ -757,7 +757,8 @@
                *lt = LIST_NEXT(*lt, l_sibling);
        }
 
-       while (*lt != NULL && !lwp_alive(*lt))
+       while (*lt != NULL && (!lwp_alive(*lt) ||
+              ((*lt)->l_flag & LW_SYSTEM) != 0))
                *lt = LIST_NEXT(*lt, l_sibling);
 
        pl.pl_lwpid = 0;
@@ -822,8 +823,8 @@
                        *lt = LIST_NEXT(*lt, l_sibling);
                }
 
-               while (*lt != NULL && !lwp_alive(*lt) &&
-                      ((*lt)->l_flag & LW_SYSTEM) != 0)
+               while (*lt != NULL && (!lwp_alive(*lt) ||
+                      ((*lt)->l_flag & LW_SYSTEM) != 0))
                        *lt = LIST_NEXT(*lt, l_sibling);
 
                if (*lt == NULL) {