netdev - Re: [PATCH net] vxlan: do not destroy fdb if register

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Message-ID: <CAMArcTXWNY6WTjuBuUVxeb3c6dTqf8wf6sHFmNL5SvsGBbPqdQ@mail.gmail.com>
Date:   Mon, 24 Jun 2019 11:18:08 +0900
From:   Taehee Yoo <ap420073@...il.com>
To:     David Miller <davem@...emloft.net>
Cc:     Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net] vxlan: do not destroy fdb if register_netdevice() is failed

On Mon, 24 Jun 2019 at 03:07, David Miller <davem@...emloft.net> wrote:
>

Hi David,

Thank you for the review!

> From: Taehee Yoo <ap420073@...il.com>
> Date: Thu, 20 Jun 2019 20:51:08 +0900
>
> > __vxlan_dev_create() destroys FDB using specific pointer which indicates
> > a fdb when error occurs.
> > But that pointer should not be used when register_netdevice() fails because
> > register_netdevice() internally destroys fdb when error occurs.
> >
> > In order to avoid un-registered dev's notification, fdb destroying routine
> > checks dev's register status before notification.
>
> Simply pass do_notify as false in this failure code path of __vxlan_dev_create(),
> thank you.

Failure path of __vxlan_dev_create() can't handle do_notify in that case
because if register_netdevice() fails it internally calls
->ndo_uninit() which is
vxlan_uninit().
vxlan_uninit() internally calls vxlan_fdb_delete_default() and it callls
vxlan_fdb_destroy().
do_notify of vxlan_fdb_destroy() in vxlan_fdb_delete_default() is always true.
So, failure path of __vxlan_dev_create() doesn't have any opportunity to
handle do_notify.

Thank you!