netdev - Re: [PATCH] genetlink: make policy common to family

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Date:   Fri, 22 Mar 2019 10:38:45 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     johannes@...solutions.net
Cc:     netdev@...r.kernel.org, dsa@...ulusnetworks.com,
        johannes.berg@...el.com
Subject: Re: [PATCH] genetlink: make policy common to family

From: Johannes Berg <johannes@...solutions.net>
Date: Thu, 21 Mar 2019 22:51:02 +0100

> From: Johannes Berg <johannes.berg@...el.com>
> 
> Since maxattr is common, the policy can't really differ sanely,
> so make it common as well.
> 
> The only user that did in fact manage to make a non-common policy
> is taskstats, which has to be really careful about it (since it's
> still using a common maxattr!). This is no longer supported, but
> we can fake it using pre_doit.
> 
> This reduces the size of e.g. nl80211.o (which has lots of commands):
> 
>    text	   data	    bss	    dec	    hex	filename
>  398745	  14323	   2240	 415308	  6564c	net/wireless/nl80211.o (before)
>  397913	  14331	   2240	 414484	  65314	net/wireless/nl80211.o (after)
> --------------------------------
>    -832      +8       0    -824
> 
> Which is obviously just 8 bytes for each command, and an added 8
> bytes for the new policy pointer. I'm not sure why the ops list is
> counted as .text though.
> 
> Most of the code transformations were done using the following spatch:
 ...
> This also gets rid of devlink_nl_cmd_region_read_dumpit() accessing
> the cb->data as ops, which we want to change in a later genl patch.
> 
> Signed-off-by: Johannes Berg <johannes.berg@...el.com>

Looks good, applied, thanks Johannes.