Hi Isaku,
Thank you for your comment.
It seems good. I think that your patch is better.
Thanks,
KAZ
From: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
Subject: Re: [Xen-ia64-devel] [PATCH] Fix a bug in xencomm_copy_from/to_guest()
Date: Wed, 27 Dec 2006 19:16:16 +0900
>
> Hi Kaz.
>
> On Wed, Dec 27, 2006 at 06:27:26PM +0900, SUZUKI Kazuhiro wrote:
> > diff -r 80c5b5914b79 xen/arch/ia64/xen/xencomm.c
> > --- a/xen/arch/ia64/xen/xencomm.c Wed Dec 20 14:55:02 2006 -0700
> > +++ b/xen/arch/ia64/xen/xencomm.c Wed Dec 27 18:03:10 2006 +0900
> > @@ -148,6 +148,13 @@ xencomm_copy_from_guest(
> > pgoffset = src_paddr % PAGE_SIZE;
> > chunksz = PAGE_SIZE - pgoffset;
> >
> > + if (chunksz <= skip) {
> > + from_pos += chunksz;
> > + skip -= chunksz;
> > + i++;
> > + continue;
> > + }
> > +
> > chunk_skip = min(chunksz, skip);
> > from_pos += chunk_skip;
> > chunksz -= chunk_skip;
>
> This condition looks odd.
> I guess the issues which you've seen is
> calling xencomm_copy_chunk_{to, from} with len = 0.
> (If I'm wrong, correct me.)
> The patch should looks like as follows.
> And xen/common/xencomm.c should modified similary too.
>
> --- xen/arch/ia64/xen/xencomm.c 2006-12-21 12:05:05.000000000 +0900
> +++ xen/arch/ia64/xen/xencomm.c.new 2006-12-27 19:12:19.000000000 +0900
> @@ -153,7 +153,7 @@ xencomm_copy_from_guest(
> chunksz -= chunk_skip;
> skip -= chunk_skip;
>
> - if (skip == 0) {
> + if (skip == 0 && chunksz > 0) {
> unsigned int bytes = min(chunksz, n - to_pos);
> int res;
>
> @@ -295,7 +295,7 @@ xencomm_copy_to_guest(
> skip -= chunk_skip;
> dest_paddr += chunk_skip;
>
> - if (skip == 0) {
> + if (skip == 0 && chunksz > 0) {
> unsigned int bytes = min(chunksz, n - from_pos);
> int res;
> --
> yamahata
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