[src/trunk]: src/sys/arch/sparc64/dev Avoid a panic if we are asked to sync a...

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

details:   https://anonhg.NetBSD.org/src/rev/ae49f4d5306a
branches:  trunk
changeset: 749674:ae49f4d5306a
user:      jdc <jdc%NetBSD.org@localhost>
date:      Sat Dec 05 16:48:26 2009 +0000

description:
Avoid a panic if we are asked to sync a zero-length map, by returning
immediately.

diffstat:

 sys/arch/sparc64/dev/iommu.c |  8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diffs (29 lines):

diff -r c4aa3e072f25 -r ae49f4d5306a sys/arch/sparc64/dev/iommu.c
--- a/sys/arch/sparc64/dev/iommu.c      Sat Dec 05 16:43:25 2009 +0000
+++ b/sys/arch/sparc64/dev/iommu.c      Sat Dec 05 16:48:26 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: iommu.c,v 1.88 2009/11/07 07:27:46 cegger Exp $        */
+/*     $NetBSD: iommu.c,v 1.89 2009/12/05 16:48:26 jdc Exp $   */
 
 /*
  * Copyright (c) 1999, 2000 Matthew R. Green
@@ -59,7 +59,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: iommu.c,v 1.88 2009/11/07 07:27:46 cegger Exp $");
+__KERNEL_RCSID(0, "$NetBSD: iommu.c,v 1.89 2009/12/05 16:48:26 jdc Exp $");
 
 #include "opt_ddb.h"
 
@@ -1000,6 +1000,10 @@
        bus_size_t len, int ops)
 {
 
+       /* If len is 0, then there is nothing to do */
+       if (len == 0)
+               return;
+
        if (ops & (BUS_DMASYNC_PREREAD | BUS_DMASYNC_PREWRITE)) {
                /* Flush the CPU then the IOMMU */
                bus_dmamap_sync(t->_parent, map, offset, len, ops);