[src/trunk]: src/sys/kern PR kern/55020: dbregs_dr?_dont_inherit_lwp test cas...

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

details:   https://anonhg.NetBSD.org/src/rev/504f0b5783fe
branches:  trunk
changeset: 849629:504f0b5783fe
user:      ad <ad%NetBSD.org@localhost>
date:      Sun Mar 08 17:04:45 2020 +0000

description:
PR kern/55020: dbregs_dr?_dont_inherit_lwp test cases fail on real hardware

lwp_wait(): make the check for deadlock much more permissive.

diffstat:

 sys/kern/kern_lwp.c |  13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)

diffs (36 lines):

diff -r 6ac5a5b86d0e -r 504f0b5783fe sys/kern/kern_lwp.c
--- a/sys/kern/kern_lwp.c       Sun Mar 08 15:21:15 2020 +0000
+++ b/sys/kern/kern_lwp.c       Sun Mar 08 17:04:45 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_lwp.c,v 1.228 2020/02/27 20:52:25 ad Exp $        */
+/*     $NetBSD: kern_lwp.c,v 1.229 2020/03/08 17:04:45 ad Exp $        */
 
 /*-
  * Copyright (c) 2001, 2006, 2007, 2008, 2009, 2019, 2020
@@ -211,7 +211,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.228 2020/02/27 20:52:25 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.229 2020/03/08 17:04:45 ad Exp $");
 
 #include "opt_ddb.h"
 #include "opt_lockdebug.h"
@@ -677,12 +677,13 @@
                }
 
                /*
-                * If all other LWPs are waiting for exits or suspends
-                * and the supply of zombies and potential zombies is
-                * exhausted, then we are about to deadlock.
+                * Break out if the process is exiting, or if all LWPs are
+                * in _lwp_wait().  There are other ways to hang the process
+                * with _lwp_wait(), but the sleep is interruptable so
+                * little point checking for them.
                 */
                if ((p->p_sflag & PS_WEXIT) != 0 ||
-                   p->p_nrlwps + p->p_nzlwps - p->p_ndlwps <= p->p_nlwpwait) {
+                   p->p_nlwpwait == p->p_nlwps) {
                        error = EDEADLK;
                        break;
                }