Linux Virtualization - Aug 2010 - [PATCH 1/6] staging: hv: Fixed bounce kmap problem by using correct index

From: Hank Janssen <hjanssen at microsoft.com> 

Fixed bounce offset kmap problem by using correct index

Signed-off-by:Hank Janssen <hjanssen at microsoft.com>
Signed-off-by:Haiyang Zhang <haiyangz at microsoft.com>

---
 drivers/staging/hv/storvsc_drv.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/hv/storvsc_drv.c b/drivers/staging/hv/storvsc_drv.c
index 075b61b..3b9ccb0 100644
--- a/drivers/staging/hv/storvsc_drv.c
+++ b/drivers/staging/hv/storvsc_drv.c
@@ -495,7 +495,7 @@ static unsigned int copy_to_bounce_buffer(struct scatterlist
*orig_sgl,
 
 		/* ASSERT(orig_sgl[i].offset + orig_sgl[i].length <= PAGE_SIZE); */
 
-		if (j == 0)
+		if (bounce_addr == 0)
 			bounce_addr = (unsigned long)kmap_atomic(sg_page((&bounce_sgl[j])),
KM_IRQ0);
 
 		while (srclen) {
@@ -556,7 +556,7 @@ static unsigned int copy_from_bounce_buffer(struct
scatterlist *orig_sgl,
 		destlen = orig_sgl[i].length;
 		/* ASSERT(orig_sgl[i].offset + orig_sgl[i].length <= PAGE_SIZE); */
 
-		if (j == 0)
+		if (bounce_addr == 0)
 			bounce_addr = (unsigned long)kmap_atomic(sg_page((&bounce_sgl[j])),
KM_IRQ0);
 
 		while (destlen) {
--
1.6.0.2

On Tue, Aug 03, 2010 at 05:31:51PM +0000, Hank Janssen
wrote:
> From: Hank Janssen <hjanssen at microsoft.com> 
> 
> Fixed bounce offset kmap problem by using correct index
Is this a bugfix that needs to go to previous kernel releases?  If so,
which ones?  What is the symptom of the problem here?

thanks,

greg k-h

And then Greg spoke:
>>On Tue, Aug 03, 2010 at 05:31:51PM +0000, Hank Janssen wrote:
>> From: Hank Janssen <hjanssen at microsoft.com>
>> 
> >Fixed bounce offset kmap problem by using correct index
>
>Is this a bugfix that needs to go to previous kernel releases?  If so, which
ones?  What is the symptom of the problem here?
Yes, this should be backported to all stable kernel releases that have the
Hyper-V drivers In them.

The symptom of the problem is that in some NAS appliances this problem
represents
Itself by a unresponsive VM under a load with many clients writing small files.

I actually goofed up in my previous code and used an incorrect index number
For this part of the code. It should have shown up in more situations than what
I have seen oddly enough.

Hank.

On Wed, Aug 04, 2010 at 05:17:21PM +0000, Hank Janssen
wrote:
> 
> >And then Greg spoke:
> >> And then Greg spoke:
> > >>>On Tue, Aug 03, 2010 at 05:31:51PM +0000, Hank Janssen
wrote:
> > >>> From: Hank Janssen <hjanssen at microsoft.com>
> > >>> 
> > >> >Fixed bounce offset kmap problem by using correct index
> > >>
> 
> SNIP
> 
> > > I actually goofed up in my previous code and used an incorrect
index
> > > number For this part of the code. It should have shown up in more
> > > situations than what I have seen oddly enough.
> >
> >Please provide this type of information in the changelog section.
> >
> >If you want something backported to older stable kernels, add a:
> >	Cc: stable <stable at kernel.org>
> 
> I will re-submit all 5 patches and CC the stable mailing list on it as
well.
5?  I see 6 of them here :)

thanks,

greg k-h

On Aug 4, 2010, at 11:26, Greg KH <gregkh at suse.de> wrote:
> On Wed, Aug 04, 2010 at 05:17:21PM +0000, Hank Janssen wrote:
>>> 
>> 
>> I will re-submit all 5 patches and CC the stable mailing list on it as
well.
> 
> 5?  I see 6 of them here :)
> 
> thanks,
> 
> greg k-h
> 
True but anise you rejected the todo patch there will only be 5.
Unless you are willing to take the todo patch. :)

Hank.

On Wed, Aug 04, 2010 at 06:50:24PM +0000, Hank Janssen
wrote:
> On Aug 4, 2010, at 11:26, Greg KH <gregkh at suse.de> wrote:
> > On Wed, Aug 04, 2010 at 05:17:21PM +0000, Hank Janssen wrote:
> >>> 
> >> 
> >> I will re-submit all 5 patches and CC the stable mailing list on
it as well.
> > 
> > 5?  I see 6 of them here :)
> > 
> > thanks,
> > 
> > greg k-h
> > 
> 
> True but anise you rejected the todo patch there will only be 5.
> Unless you are willing to take the todo patch. :)
Doh, you are right, nevermind :)

thanks,

greg k-h