[src/trunk]: src/sys/kern crashme(9): New kernel_lock_spinout crasher.

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

details:   https://anonhg.NetBSD.org/src/rev/81467321d495
branches:  trunk
changeset: 369413:81467321d495
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Tue Aug 16 10:24:17 2022 +0000

description:
crashme(9): New kernel_lock_spinout crasher.

This assumes that something will eventually try to take the kernel
lock and, after spinning for a while, spin out and crash -- so for
now it's only enabled under LOCKDEBUG, without which the kernel lock
spins forever.

diffstat:

 sys/kern/kern_crashme.c |  22 +++++++++++++++++++++-
 1 files changed, 21 insertions(+), 1 deletions(-)

diffs (47 lines):

diff -r 0a86751562dc -r 81467321d495 sys/kern/kern_crashme.c
--- a/sys/kern/kern_crashme.c   Tue Aug 16 09:03:04 2022 +0000
+++ b/sys/kern/kern_crashme.c   Tue Aug 16 10:24:17 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_crashme.c,v 1.5 2021/11/27 14:11:14 riastradh Exp $       */
+/*     $NetBSD: kern_crashme.c,v 1.6 2022/08/16 10:24:17 riastradh Exp $       */
 
 /*
  * Copyright (c) 2018, 2019 Matthew R. Green
@@ -63,6 +63,9 @@
 #ifdef DDB
 static int crashme_ddb(int);
 #endif
+#ifdef LOCKDEBUG
+static int crashme_kernel_lock_spinout(int);
+#endif
 
 #define CMNODE(name, lname, func)      \
     {                                  \
@@ -78,6 +81,10 @@
 #ifdef DDB
     CMNODE("ddb", "enter ddb directly", crashme_ddb),
 #endif
+#ifdef LOCKDEBUG
+    CMNODE("kernel_lock_spinout", "infinite kernel lock",
+       crashme_kernel_lock_spinout),
+#endif
 };
 static crashme_node *first_node;
 static kmutex_t crashme_lock;
@@ -270,3 +277,16 @@
        return 0;
 }
 #endif
+
+#ifdef LOCKDEBUG
+static int
+crashme_kernel_lock_spinout(int flags)
+{
+
+       KERNEL_LOCK(1, NULL);
+       for (;;)
+               __insn_barrier();
+       KERNEL_UNLOCK_ONE(NULL);
+       return 0;
+}
+#endif