Re: [PATCH 00/11] DMA sync errors

Stephen Hemminger
2010-01-21T00:34:27Z

On Wed, 20 Jan 2010 16:18:05 -0800 (PST)
David Miller <davem@davemloft.net> wrote:

> From: Stephen Hemminger <shemminger@vyatta.com>
> Date: Wed, 20 Jan 2010 15:28:32 -0800
>
> > This should fix the dma-debug API code (and documentation), to
> > avoid false positives when sync is done on a partial map.
> >
> > Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
> ...
> > --- a/lib/dma-debug.c 2010-01-20 15:22:55.919519883 -0800
> > +++ b/lib/dma-debug.c 2010-01-20 15:26:31.648895638 -0800
> > @@ -285,11 +285,9 @@ static struct dma_debug_entry *hash_buck
> > }
> >
> > /*
> > - * If we have multiple matches but no perfect-fit, just return
> > - * NULL.
> > + * If we have multiple matches but no perfect-fit
> > + * return best value and let caller deal with it.
> > */
> > - ret = (matches == 1) ? ret : NULL;
> > -
> > return ret;
> > }
> >
>
> I think you have to enforce a perfect-fit match for the
> non-SYNC cases.
>
> check_sync() can pass in 'true' for a new bool argument "partial_ok"
> added to hash_bucket_find() whereas check_unmap() can pass 'false'.
>
> get_nr_mapped_entries() should pass 'false' as well.

check_unmap has checks for different size, different type,
call_ents, direction etc.

The code for get_nr_mapped_entries() is the only question;
it is used by unmap_sg() and probably needs perfect match only.