netdev - Re: [PATCH net] enic: Avoid removing IPv6 address when updating rings size.

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Message-ID: <CADEbmW3NXWMPBiTtX-v2XBLMTVgPifF9YW9qxJ=AkVYppfwiOw@mail.gmail.com>
Date: Mon, 24 Feb 2025 12:16:32 +0100
From: Michal Schmidt <mschmidt@...hat.com>
To: Mohammad Heib <mheib@...hat.com>
Cc: netdev@...r.kernel.org, benve@...co.com, satishkh@...co.com
Subject: Re: [PATCH net] enic: Avoid removing IPv6 address when updating rings size.

On Sun, Feb 23, 2025 at 10:42 PM Mohammad Heib <mheib@...hat.com> wrote:
> Currently, the enic driver calls the dev_close function to temporarily
> shut down the device before updating the device rings. This call
> triggers a NETDEV_DOWN event, which is sent to the network stack via the
> network notifier.
>
> When the IPv6 stack receives such an event, it removes the IPv6
> addresses from the affected device, keeping only the permanent
> addresses. This behavior is inconsistent with other network drivers and
> can lead to traffic loss, requiring reconfiguration of IPv6 addresses
> after every ring update.
>
> To avoid this behavior, this patch temporarily sets the interface config
> `keep_addr_on_down` to 1 before closing the device during the rings
> update, and restores the original value of `keep_addr_on_down` after
> updating the device rings, this will prevent the ipv6 stack from
> removing the current ipv6 addresses during the rings update.

That's icky. Can you instead avoid using the dev_close()/dev_open()?
Michal