netdev - Re: [PATCH net] lwtunnel: fix autoload of lwt modules

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Message-ID: <8b621810-f7b3-05bb-413b-29389125c6ea@cumulusnetworks.com>
Date:   Tue, 17 Jan 2017 10:07:15 -0700
From:   David Ahern <dsa@...ulusnetworks.com>
To:     Robert Shearman <rshearma@...cade.com>, netdev@...r.kernel.org,
        roopa <roopa@...ulusnetworks.com>
Subject: Re: [PATCH net] lwtunnel: fix autoload of lwt modules

On 1/17/17 3:04 AM, Robert Shearman wrote:
> Is it safe to release the rtnl lock here? E.g. neither fib_get_nhs nor fib_create_info take a reference on the device and further up inet_rtm_newroute has a pointer to the struct fib_table without taking a reference.

fib tables can not be deleted so that reference is safe. You are right about the dev reference in the IPv4 path but the thing is build_state does not need the device reference.

Roopa: do you recall why dev is passed to build_state? Nothing about the encap should require a device reference and none of the current encaps use it.

> 
> Unfortunately, I think more invasive changes are required to solve this. I'm happy to work on solving this.

I have a patch that removes passing dev to build_state. Walking the remainder of the code I do not see any more references that would be affected by dropping rtnl here on the add path. Still looking at the delete path.