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Date: Thu, 28 Mar 2024 10:10:53 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: Breno Leitao <leitao@debian.org>, "David S. Miller"
 <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, "Paolo Abeni"
 <pabeni@redhat.com>, <quic_jjohnson@quicinc.com>, <kvalo@kernel.org>,
 <leon@kernel.org>, <dennis.dalessandro@cornelisnetworks.com>, Jiri Pirko
 <jiri@resnulli.us>, Simon Horman <horms@kernel.org>, Daniel Borkmann
 <daniel@iogearbox.net>, Lorenzo Bianconi <lorenzo@kernel.org>, Coco Li
 <lixiaoyan@google.com>, "open list:NETWORKING DRIVERS"
 <netdev@vger.kernel.org>, open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net-next] net: create a dummy net_device allocator
Message-ID: <20240328101053.69a968ec@kernel.org>
In-Reply-To: <10d89693-21af-4560-a088-d58d16cbb9dd@intel.com>
References: <20240327200809.512867-1-leitao@debian.org>
	<10d89693-21af-4560-a088-d58d16cbb9dd@intel.com>
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On Thu, 28 Mar 2024 16:02:12 +0100 Alexander Lobakin wrote:
> > +/**
> > + * alloc_netdev_dummy - Allocate and initialize a dummy net device.
> > + * @sizeof_priv: size of private data to allocate space for
> > + * @name: device name format string
> > + */
> > +struct net_device *alloc_netdev_dummy(int sizeof_priv, const char *name)  
> 
> Since the users of init_dummy_netdev embed &net_device into their
> private structures, do we need sizeof_priv here at all? Or maybe we
> could unconditionally pass 0?

FWIW similar thing could be said about @name, if we never intend to
register the device - it will never have a legitimate (user visible)
name. So we may be better off naming them "dummy#" or some such.
No strong preference, tho. Adding params back later may be a bit
of a pain.

> > +{
> > +	return alloc_netdev(sizeof_priv, name, NET_NAME_UNKNOWN,
> > +			    init_dummy_netdev_core);
> > +}
> > +EXPORT_SYMBOL_GPL(alloc_netdev_dummy);
> > +
> >  /**
> >   *	synchronize_net -  Synchronize with packet receive processing
> >   *  
> 
> As Jakub mentioned, you need to introduce consumers of the functionality
> you add within the same series. Personally, I'd like to see a series
> with agressive conversion of all the affected drivers from
> init_dummy_netdev() to alloc_dummy_netdev() and final removal of
> init_dummy_netdev() :D

We can, and put it on a shared branch so other trees can also pull in
the conversions. No preference on my side, tho. I think that Breno
doesn't have any of the HW in question, so starting with one and making
sure it works could be more "work conserving", than redoing all
patches..