[src/trunk]: src/sys/uvm uvm_anon_freelst:

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

details:   https://anonhg.NetBSD.org/src/rev/5a97e9180ae7
branches:  trunk
changeset: 768529:5a97e9180ae7
user:      yamt <yamt%NetBSD.org@localhost>
date:      Thu Aug 18 14:13:02 2011 +0000

description:
uvm_anon_freelst:
- clear an_link/an_ref when deferring anon disposal.  otherwise others can
  see bogus an_ref.
- fix the code to remove anon from the list.

diffstat:

 sys/uvm/uvm_anon.c |  23 ++++++++++-------------
 1 files changed, 10 insertions(+), 13 deletions(-)

diffs (49 lines):

diff -r 2dcee2df29a7 -r 5a97e9180ae7 sys/uvm/uvm_anon.c
--- a/sys/uvm/uvm_anon.c        Thu Aug 18 13:47:22 2011 +0000
+++ b/sys/uvm/uvm_anon.c        Thu Aug 18 14:13:02 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uvm_anon.c,v 1.60 2011/08/14 01:20:33 rmind Exp $      */
+/*     $NetBSD: uvm_anon.c,v 1.61 2011/08/18 14:13:02 yamt Exp $       */
 
 /*
  * Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_anon.c,v 1.60 2011/08/14 01:20:33 rmind Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_anon.c,v 1.61 2011/08/18 14:13:02 yamt Exp $");
 
 #include "opt_uvmhist.h"
 
@@ -214,22 +214,19 @@
 void
 uvm_anon_freelst(struct vm_amap *amap, struct vm_anon *anonlst)
 {
-       struct vm_anon *anon = anonlst, *prev = NULL, *next;
+       struct vm_anon *anon;
+       struct vm_anon **anonp = &anonlst;
 
        KASSERT(mutex_owned(amap->am_lock));
-
-       while (anon) {
-               next = anon->an_link;
+       while ((anon = *anonp) != NULL) {
                if (!uvm_anon_dispose(anon)) {
                        /* Do not free this anon. */
-                       if (prev) {
-                               prev->an_link = next;
-                       } else {
-                               anonlst = next;
-                       }
+                       *anonp = anon->an_link;
+                       /* Note: clears an_ref as well. */
+                       anon->an_link = NULL;
+               } else {
+                       anonp = &anon->an_link;
                }
-               prev = anon;
-               anon = next;
        }
        amap_unlock(amap);