Re: [PATCH net-next 6/6] tg3: Make the RSS indir tbl admin configurable

[Ben Hutchings <bhutchings@solarflare.com>]

On Thu, 2011-12-15 at 13:03 -0800, Matt Carlson wrote:
> On Wed, Dec 14, 2011 at 01:50:59PM -0800, Ben Hutchings wrote:
> > On Wed, 2011-12-14 at 13:10 -0800, Matt Carlson wrote:
[...]
> > > +	if (!indir->size) {
> > > +		indir->size = TG3_RSS_INDIR_TBL_SIZE;
> > > +		return 0;
> > > +	}
> > > +
> > > +	if (indir->size != TG3_RSS_INDIR_TBL_SIZE)
> > > +		return -EINVAL;
> > 
> > This is enough to make the ethtool command work, but you're really
> > supposed to copy min(indir->size, TG3_RSS_INDIR_TBL_SIZE) entries.
> 
> Could you elaborate on this?  I'm confused because I can't figure out
> how returning half of an indirection table could be useful.

It's a generalisation of the zero-length and full-length cases.  But no,
it isn't very useful, nor did I actually specify that anywhere!

Maybe there should be a driver operation to get the table size, and then
the core can make sure that drivers only ever deal with full-table
buffers.  Though that wouldn't cover your reset-to-default case.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.