[src/trunk]: src/sys/kern Improve debugging functions

[ozaki-r <ozaki-r%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/93cb15288ef8
branches:  trunk
changeset: 358142:93cb15288ef8
user:      ozaki-r <ozaki-r%NetBSD.org@localhost>
date:      Thu Dec 14 05:45:55 2017 +0000

description:
Improve debugging functions

- Make psref_check_duplication check just if a given psref is on the list
  - It checked both psref and target
  - Suggested by riastradh@ some time ago
- Add psref_check_existence that checks a releasing psref is surely on the list

diffstat:

 sys/kern/subr_psref.c |  46 ++++++++++++++++++++++++++++++++++------------
 1 files changed, 34 insertions(+), 12 deletions(-)

diffs (80 lines):

diff -r 1f20798b46c5 -r 93cb15288ef8 sys/kern/subr_psref.c
--- a/sys/kern/subr_psref.c     Thu Dec 14 05:43:14 2017 +0000
+++ b/sys/kern/subr_psref.c     Thu Dec 14 05:45:55 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: subr_psref.c,v 1.8 2017/12/11 02:33:17 knakahara Exp $ */
+/*     $NetBSD: subr_psref.c,v 1.9 2017/12/14 05:45:55 ozaki-r Exp $   */
 
 /*-
  * Copyright (c) 2016 The NetBSD Foundation, Inc.
@@ -64,7 +64,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_psref.c,v 1.8 2017/12/11 02:33:17 knakahara Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_psref.c,v 1.9 2017/12/14 05:45:55 ozaki-r Exp $");
 
 #include <sys/types.h>
 #include <sys/condvar.h>
@@ -187,22 +187,40 @@
 }
 
 #ifdef DEBUG
+static bool
+psref_exist(struct psref_cpu *pcpu, struct psref *psref)
+{
+       struct psref *_psref;
+
+       SLIST_FOREACH(_psref, &pcpu->pcpu_head, psref_entry) {
+               if (_psref == psref)
+                       return true;
+       }
+       return false;
+}
+
 static void
 psref_check_duplication(struct psref_cpu *pcpu, struct psref *psref,
     const struct psref_target *target)
 {
        bool found = false;
-       struct psref *_psref;
+
+       found = psref_exist(pcpu, psref);
+       if (found) {
+               panic("The psref is already in the list (acquiring twice?): "
+                   "psref=%p target=%p", psref, target);
+       }
+}
 
-       SLIST_FOREACH(_psref, &pcpu->pcpu_head, psref_entry) {
-               if (_psref == psref &&
-                   _psref->psref_target == target) {
-                       found = true;
-                       break;
-               }
-       }
-       if (found) {
-               panic("trying to acquire a target twice with the same psref: "
+static void
+psref_check_existence(struct psref_cpu *pcpu, struct psref *psref,
+    const struct psref_target *target)
+{
+       bool found = false;
+
+       found = psref_exist(pcpu, psref);
+       if (!found) {
+               panic("The psref isn't in the list (releasing unused psref?): "
                    "psref=%p target=%p", psref, target);
        }
 }
@@ -304,6 +322,10 @@
         */
        s = splraiseipl(class->prc_iplcookie);
        pcpu = percpu_getref(class->prc_percpu);
+#ifdef DEBUG
+       /* Sanity-check if the target is surely acquired before.  */
+       psref_check_existence(pcpu, psref, target);
+#endif
        SLIST_REMOVE(&pcpu->pcpu_head, psref, psref, psref_entry);
        percpu_putref(class->prc_percpu);
        splx(s);