netdev - Re: [PATCH net-next 0/4] vxlan: fix default fdb entry user-space notify ordering/race

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Date:   Sat, 07 Jul 2018 20:23:04 +0900 (KST)
From:   David Miller <davem@...emloft.net>
To:     roopa@...ulusnetworks.com
Cc:     netdev@...r.kernel.org, jbenc@...hat.com,
        mike.rapoport@...ellosystems.com, stephen@...workplumber.org
Subject: Re: [PATCH net-next 0/4] vxlan: fix default fdb entry user-space
 notify ordering/race

From: Roopa Prabhu <roopa@...ulusnetworks.com>
Date: Wed,  4 Jul 2018 16:46:28 -0700

> From: Roopa Prabhu <roopa@...ulusnetworks.com>
> 
> Problem:
> In vxlan_newlink, a default fdb entry is added before register_netdev.
> The default fdb creation function notifies user-space of the
> fdb entry on the vxlan device which user-space does not know about yet.
> (RTM_NEWNEIGH goes before RTM_NEWLINK for the same ifindex).
> 
> This series fixes the user-space netlink notification ordering issue
> with the following changes:
> - decouple fdb notify from fdb create.
> - Move fdb notify after register_netdev.
> - modify rtnl_configure_link to allow configuring a link early.
> - Call rtnl_configure_link in vxlan newlink handler to notify
> userspace about the newlink before fdb notify and
> hence avoiding the user-space race.
> 
> Fixes: afbd8bae9c79 ("vxlan: add implicit fdb entry for default destination")
> Signed-off-by: Roopa Prabhu <roopa@...ulusnetworks.com>

This is quite an old bug (circa v3.11).  Maybe after this cooks for some
time in net-next you can also submit it for 'net' and we can thus send
it off to -stable as well?

Applied to net-next, thanks.