Subject: Re: [RFC 2.6.10 7/22] xfrm: Allow device drivers to force recalculation of offloads

From: "David S. Miller" <[email-masked]>
Date: Fri, 21 Jan 2005 15:23:58 -0800

On Thu, 30 Dec 2004 03:48:35 -0500
David Dillow <[email-masked]> wrote:

> # This is a BitKeeper generated diff -Nru style patch.
> #
> # ChangeSet
> #   2004/12/30 00:37:44-05:00 [email-masked] 
> #   Give device drivers a method to allow the use of crypto
> #   offload features for existing xfrm_states and bundles, as
> #   well as dynamically remove crypto offload capabilities.
> #   
> #   Signed-off-by: David Dillow <[email-masked]>

This change looks fine, but it reminds me of something.

We have to make sure there is no way for xfrm_offloads to
refer to a device when it is brought down.

One way to ensure that, is to make each xfrm_offload attached
grab a reference to the device it is for.  The refcounting will
help catch cases where stale xfrm_offload are around at
unregister_netdev() time.