From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [Bugme-new] [Bug 8107] New: dev->header_cache_update has a
 random value
Date: Thu, 01 Mar 2007 17:33:10 -0800 (PST)
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From: Stephen Hemminger <shemminger@linux-foundation.org>
Date: Thu, 1 Mar 2007 14:37:27 -0800

> Not necessary, since any network device must already allocated by
> alloc_netdev() and it initializes the whole struct to 0 (NULL).

It is in this case, unfortunately, HDLC protocols can be registers
several times before the device is brought up and protocol changes
become disallowed.

So you can attach one, then a second one, and the second one has
to explicitly initialize the pointers potentially set by the
first one.

On the other hand, you could say that it's the protocol
->detach() method's responsibility to NULL out these things
instead of leaving references to function pointers of
a module that's about the be unloaded.