Re: [RFC] NAPI as kobject proposal

Stephen Hemminger
2010-02-03T21:42:09Z

On Wed, 3 Feb 2010 21:26:41 +0000
Al Viro <viro@ZenIV.linux.org.uk> wrote:

> On Wed, Feb 03, 2010 at 09:23:36PM +0000, Ben Hutchings wrote:
> > On Fri, 2010-01-29 at 10:18 -0800, Stephen Hemminger wrote:
> > > The NAPI interface structure in current kernels is managed by the driver.
> > > As part of receive packet steering there is a requirement to add an
> > > additional parameter to this for the CPU map. And this map needs to
> > > have an API to set it.
> > >
> > > The right way to do this in the kernel model is to make NAPI into
> > > a kobject and associate it back with the network device (parent).
> > > This isn't wildly difficult but does change some of the API for
> > > network device drivers because:
> > > 1. They need to handle another possible error on setup
> > > 2. NAPI object needs to be dynamically allocated
> > > separately (not as part of netdev_priv)
> > > 3. Driver should pass index that can be uses as part of
> > > name (easier than scanning)
>
> 4. Lifetime rules become oh-so-fscking-interesting?

My original proposal doesn't go far enough. I am doing a bigger
version that changes API to:
napi_alloc / napi_release

The lifetime problem isn't that bad because the napi is a child
of network device object. Make it a child bus object is a bigger
problem because then network device can come and go.

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