[src/trunk]: src/sys/kern KERNEL_LOCK(9): Send an IPI to print holder's stack...

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

details:   https://anonhg.NetBSD.org/src/rev/2dce4a344113
branches:  trunk
changeset: 369406:2dce4a344113
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Tue Aug 16 00:26:39 2022 +0000

description:
KERNEL_LOCK(9): Send an IPI to print holder's stack trace on spinout.

diffstat:

 sys/kern/kern_lock.c |  30 ++++++++++++++++++++++++++++--
 1 files changed, 28 insertions(+), 2 deletions(-)

diffs (72 lines):

diff -r 230826f1b7a4 -r 2dce4a344113 sys/kern/kern_lock.c
--- a/sys/kern/kern_lock.c      Mon Aug 15 18:06:04 2022 +0000
+++ b/sys/kern/kern_lock.c      Tue Aug 16 00:26:39 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_lock.c,v 1.173 2021/10/31 16:26:26 skrll Exp $    */
+/*     $NetBSD: kern_lock.c,v 1.174 2022/08/16 00:26:39 riastradh Exp $        */
 
 /*-
  * Copyright (c) 2002, 2006, 2007, 2008, 2009, 2020 The NetBSD Foundation, Inc.
@@ -31,7 +31,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_lock.c,v 1.173 2021/10/31 16:26:26 skrll Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_lock.c,v 1.174 2022/08/16 00:26:39 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_lockdebug.h"
@@ -134,6 +134,22 @@
        .lo_dump = _kernel_lock_dump,
 };
 
+#ifdef LOCKDEBUG
+
+#include <ddb/ddb.h>
+
+static void
+kernel_lock_trace_ipi(void *cookie)
+{
+
+       printf("%s[%d %s]: hogging kernel lock\n", cpu_name(curcpu()),
+           curlwp->l_lid,
+           curlwp->l_name ? curlwp->l_name : curproc->p_comm);
+       db_stacktrace();
+}
+
+#endif
+
 /*
  * Initialize the kernel lock.
  */
@@ -177,6 +193,7 @@
        LOCKSTAT_FLAG(lsflag);
        struct lwp *owant;
 #ifdef LOCKDEBUG
+       static struct cpu_info *kernel_lock_holder;
        u_int spins = 0;
 #endif
        int s;
@@ -235,6 +252,11 @@
 #ifdef LOCKDEBUG
                        if (SPINLOCK_SPINOUT(spins)) {
                                extern int start_init_exec;
+                               ipi_msg_t msg = {
+                                       .func = kernel_lock_trace_ipi,
+                               };
+                               ipi_unicast(&msg, kernel_lock_holder);
+                               ipi_wait(&msg);
                                if (start_init_exec)
                                        _KERNEL_LOCK_ABORT("spinout");
                        }
@@ -278,6 +300,10 @@
 #ifndef __HAVE_ATOMIC_AS_MEMBAR
        membar_enter();
 #endif
+
+#ifdef LOCKDEBUG
+       kernel_lock_holder = curcpu();
+#endif
 }
 
 /*