[src/trunk]: src/sys/kern Use separate temporaries for the 'int' percentage a...

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

details:   https://anonhg.NetBSD.org/src/rev/6fe176b64438
branches:  trunk
changeset: 779570:6fe176b64438
user:      dsl <dsl%NetBSD.org@localhost>
date:      Sun Jun 03 16:23:44 2012 +0000

description:
Use separate temporaries for the 'int' percentage and the 'long'
  water marks.
Previous paniced on sparc64 due to a misaligned copy.

diffstat:

 sys/kern/vfs_bio.c |  28 +++++++++++++++++-----------
 1 files changed, 17 insertions(+), 11 deletions(-)

diffs (65 lines):

diff -r 8a952cb36757 -r 6fe176b64438 sys/kern/vfs_bio.c
--- a/sys/kern/vfs_bio.c        Sun Jun 03 13:52:46 2012 +0000
+++ b/sys/kern/vfs_bio.c        Sun Jun 03 16:23:44 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_bio.c,v 1.238 2012/06/03 11:37:44 dsl Exp $        */
+/*     $NetBSD: vfs_bio.c,v 1.239 2012/06/03 16:23:44 dsl Exp $        */
 
 /*-
  * Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc.
@@ -123,7 +123,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.238 2012/06/03 11:37:44 dsl Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.239 2012/06/03 16:23:44 dsl Exp $");
 
 #include "opt_bufcache.h"
 
@@ -1732,12 +1732,18 @@
 {
        int error, rv;
        struct sysctlnode node;
-       union u_int_long { unsigned int i; unsigned long l; } t;
+       unsigned int temp_bufcache;
+       unsigned long temp_water;
 
        /* Take a copy of the supplied node and its data */
        node = *rnode;
-       node.sysctl_data = &t;
-       t = *(union u_int_long *)rnode->sysctl_data;
+       if (node.sysctl_data == &bufcache) {
+           node.sysctl_data = &temp_bufcache;
+           temp_bufcache = *(unsigned int *)rnode->sysctl_data;
+       } else {
+           node.sysctl_data = &temp_water;
+           temp_water = *(unsigned long *)rnode->sysctl_data;
+       }
 
        /* Update the copy */
        error = sysctl_lookup(SYSCTLFN_CALL(&node));
@@ -1745,18 +1751,18 @@
                return (error);
 
        if (rnode->sysctl_data == &bufcache) {
-               if (t.i > 100)
+               if (temp_bufcache > 100)
                        return (EINVAL);
-               bufcache = t.i;
+               bufcache = temp_bufcache;
                buf_setwm();
        } else if (rnode->sysctl_data == &bufmem_lowater) {
-               if (bufmem_hiwater - t.l < 16)
+               if (bufmem_hiwater - temp_water < 16)
                        return (EINVAL);
-               bufmem_lowater = t.l;
+               bufmem_lowater = temp_water;
        } else if (rnode->sysctl_data == &bufmem_hiwater) {
-               if (t.l - bufmem_lowater < 16)
+               if (temp_water - bufmem_lowater < 16)
                        return (EINVAL);
-               bufmem_hiwater = t.l;
+               bufmem_hiwater = temp_water;
        } else
                return (EINVAL);