netdev - Re: [PATCH net-next 2/2] sunvnet: vnet_start

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Message-ID: <1412194526.16704.61.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Wed, 01 Oct 2014 13:15:26 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Sowmini Varadhan <sowmini.varadhan@...cle.com>
Cc:	davem@...emloft.net, raghuram.kothakota@...cle.com,
	netdev@...r.kernel.org
Subject: Re: [PATCH net-next 2/2] sunvnet: vnet_start_xmit() must hold a
 refcnt on port.

On Wed, 2014-10-01 at 15:44 -0400, Sowmini Varadhan wrote:
> On (10/01/14 12:05), Eric Dumazet wrote:
> > 
> > Hmpff... This calls for rcu protection here !
> > 
> 
> I did consider that, but given that the lists containing the ports are
> accessed in multiple contexts, some of which can sleep, and given that
> the vnet port is similar in spirit to the net_device, I followed the
> net_device model of dev_put etc.

dev_put() uses per cpu variables, an order of magnitude faster than a
atomic put/get :(



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