[src/trunk]: src/sys Catch a leaked hold of kernel_lock sooner with DIAGNOSTI...

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

details:   https://anonhg.NetBSD.org/src/rev/c388726bc08e
branches:  trunk
changeset: 848249:c388726bc08e
user:      ad <ad%NetBSD.org@localhost>
date:      Wed Jan 22 12:23:04 2020 +0000

description:
Catch a leaked hold of kernel_lock sooner with DIAGNOSTIC and make the
message a bit more informative.

diffstat:

 sys/kern/kern_exit.c |   5 +++--
 sys/kern/kern_lwp.c  |  11 ++++++-----
 sys/sys/userret.h    |   7 ++++---
 3 files changed, 13 insertions(+), 10 deletions(-)

diffs (92 lines):

diff -r 2a63c7bb8bff -r c388726bc08e sys/kern/kern_exit.c
--- a/sys/kern/kern_exit.c      Wed Jan 22 11:38:54 2020 +0000
+++ b/sys/kern/kern_exit.c      Wed Jan 22 12:23:04 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_exit.c,v 1.279 2020/01/08 17:38:42 ad Exp $       */
+/*     $NetBSD: kern_exit.c,v 1.280 2020/01/22 12:23:04 ad Exp $       */
 
 /*-
  * Copyright (c) 1998, 1999, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -67,7 +67,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.279 2020/01/08 17:38:42 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.280 2020/01/22 12:23:04 ad Exp $");
 
 #include "opt_ktrace.h"
 #include "opt_dtrace.h"
@@ -206,6 +206,7 @@
 
        /* Verify that we hold no locks other than p->p_lock. */
        LOCKDEBUG_BARRIER(p->p_lock, 0);
+       KASSERTMSG(curcpu()->ci_biglock_count == 0, "kernel_lock leaked");
        KASSERT(mutex_owned(p->p_lock));
        KASSERT(p->p_vmspace != NULL);
 
diff -r 2a63c7bb8bff -r c388726bc08e sys/kern/kern_lwp.c
--- a/sys/kern/kern_lwp.c       Wed Jan 22 11:38:54 2020 +0000
+++ b/sys/kern/kern_lwp.c       Wed Jan 22 12:23:04 2020 +0000
@@ -1,7 +1,8 @@
-/*     $NetBSD: kern_lwp.c,v 1.219 2020/01/12 13:15:08 ad Exp $        */
+/*     $NetBSD: kern_lwp.c,v 1.220 2020/01/22 12:23:04 ad Exp $        */
 
 /*-
- * Copyright (c) 2001, 2006, 2007, 2008, 2009, 2019 The NetBSD Foundation, Inc.
+ * Copyright (c) 2001, 2006, 2007, 2008, 2009, 2019, 2020
+ *     The NetBSD Foundation, Inc.
  * All rights reserved.
  *
  * This code is derived from software contributed to The NetBSD Foundation
@@ -209,7 +210,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.219 2020/01/12 13:15:08 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.220 2020/01/22 12:23:04 ad Exp $");
 
 #include "opt_ddb.h"
 #include "opt_lockdebug.h"
@@ -1063,8 +1064,9 @@
 
        SDT_PROBE(proc, kernel, , lwp__exit, l, 0, 0, 0, 0);
 
-       /* Verify that we hold no locks */
+       /* Verify that we hold no locks; for DIAGNOSTIC check kernel_lock. */
        LOCKDEBUG_BARRIER(NULL, 0);
+       KASSERTMSG(curcpu()->ci_biglock_count == 0, "kernel_lock leaked");
 
        /*
         * If we are the last live LWP in a process, we need to exit the
@@ -1080,7 +1082,6 @@
        if (p->p_nlwps - p->p_nzlwps == 1) {
                KASSERT(current == true);
                KASSERT(p != &proc0);
-               /* XXXSMP kernel_lock not held */
                exit1(l, 0, 0);
                /* NOTREACHED */
        }
diff -r 2a63c7bb8bff -r c388726bc08e sys/sys/userret.h
--- a/sys/sys/userret.h Wed Jan 22 11:38:54 2020 +0000
+++ b/sys/sys/userret.h Wed Jan 22 12:23:04 2020 +0000
@@ -1,7 +1,8 @@
-/*     $NetBSD: userret.h,v 1.31 2019/11/30 17:49:03 ad Exp $  */
+/*     $NetBSD: userret.h,v 1.32 2020/01/22 12:23:04 ad Exp $  */
 
 /*-
- * Copyright (c) 1998, 2000, 2003, 2006, 2008, 2019 The NetBSD Foundation, Inc.
+ * Copyright (c) 1998, 2000, 2003, 2006, 2008, 2019, 2020
+ *     The NetBSD Foundation, Inc.
  * All rights reserved.
  *
  * This code is derived from software contributed to The NetBSD Foundation
@@ -84,8 +85,8 @@
 
        KPREEMPT_DISABLE(l);
        ci = l->l_cpu;
+       KASSERTMSG(ci->ci_biglock_count == 0, "kernel_lock leaked");
        KASSERT(l->l_blcnt == 0);
-       KASSERT(ci->ci_biglock_count == 0);
        if (__predict_false(ci->ci_want_resched)) {
                preempt();
                ci = l->l_cpu;