netdev - Re: [PATCH net-next 0/2] rtnetlink: avoid a warning in rtnl

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Message-ID: <f1630c6d-0ac9-929f-d2f6-c739cd19fb22@gmail.com>
Date:   Wed, 28 Nov 2018 10:52:53 -0700
From:   David Ahern <dsahern@...il.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>, davem@...emloft.net
Cc:     jiri@...nulli.us, roopa@...ulusnetworks.com,
        christian.brauner@...ntu.com, netdev@...r.kernel.org,
        oss-drivers@...ronome.com
Subject: Re: [PATCH net-next 0/2] rtnetlink: avoid a warning in rtnl_newlink()

On 11/27/18 11:32 PM, Jakub Kicinski wrote:
> Hi!
> 
> I've been hoping for some time that someone more competent would fix
> the stack frame size warning in rtnl_newlink(), but looks like I'll
> have to take a stab at it myself :)  That's the only warning I see
> in most of my builds.

Somehow my CONFIG_FRAME_WARN got set to 2048 in all of my config files,
so I don't see the warning.

> 
> First patch refactors away a somewhat surprising if (1) code block.
> Reindentation will most likely cause cherry-pick problems but OTOH
> rtnl_newlink() doesn't seem to be changed often, so perhaps we can
> risk it in the name of cleaner code?

The unnecessary indentation with the if(1) has always annoyed me. I like
the cleanup, but strictly speaking if Dave objects patch 2 can be done
without it.

> 
> Second patch fixes the warning in simplest possible way.  I was
> pondering if there is any more clever solution, but I can't see it..
> rtnl_newlink() is quite long with a lot of possible execution paths
> so doing memory allocations half way through leads to very ugly
> results.

Seems like a reasonable first step and in time slave_attr can follow
suit. Those are the 2 high runners for stack usage.