[src/trunk]: src/sys/kern Fix LOCKDEBUG panic on mutex_init().

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

details:   https://anonhg.NetBSD.org/src/rev/5e84a7902210
branches:  trunk
changeset: 847305:5e84a7902210
user:      ad <ad%NetBSD.org@localhost>
date:      Tue Dec 17 18:08:15 2019 +0000

description:
Fix LOCKDEBUG panic on mutex_init().

Reported-by: syzbot+5a77339dc0a55e8d8caa%syzkaller.appspotmail.com@localhost

diffstat:

 sys/kern/kern_sleepq.c |  11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diffs (37 lines):

diff -r 57636460a841 -r 5e84a7902210 sys/kern/kern_sleepq.c
--- a/sys/kern/kern_sleepq.c    Tue Dec 17 17:51:12 2019 +0000
+++ b/sys/kern/kern_sleepq.c    Tue Dec 17 18:08:15 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_sleepq.c,v 1.55 2019/12/16 19:43:36 ad Exp $      */
+/*     $NetBSD: kern_sleepq.c,v 1.56 2019/12/17 18:08:15 ad Exp $      */
 
 /*-
  * Copyright (c) 2006, 2007, 2008, 2009, 2019 The NetBSD Foundation, Inc.
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_sleepq.c,v 1.55 2019/12/16 19:43:36 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_sleepq.c,v 1.56 2019/12/17 18:08:15 ad Exp $");
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -76,12 +76,17 @@
 void
 sleeptab_init(sleeptab_t *st)
 {
+       static bool again;
        int i;
 
        for (i = 0; i < SLEEPTAB_HASH_SIZE; i++) {
-               mutex_init(&sleepq_locks[i].lock, MUTEX_DEFAULT, IPL_SCHED);
+               if (!again) {
+                       mutex_init(&sleepq_locks[i].lock, MUTEX_DEFAULT,
+                           IPL_SCHED);
+               }
                sleepq_init(&st->st_queue[i]);
        }
+       again = true;
 }
 
 /*