netdev - Re: [PATCH] net: ipv6: fix regression of no RTM

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Date:   Mon, 18 Sep 2017 14:06:40 +0100
From:   Mike Manning <mmanning@...cade.com>
To:     David Miller <davem@...emloft.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "maheshb@...gle.com" <maheshb@...gle.com>
Subject: Re: [PATCH] net: ipv6: fix regression of no RTM_DELADDR sent after
 DAD failure

Hi,
In the absence of a reply from Mahesh, I would be most grateful for
anyone familiar with the IPv6 code to review this 1-line fix.

Or if not, then I request that the commit f784ad3d79e5 is backed out,
as its intention is to remove the redundant but harmless RTM_DELADDR
for addresses in tentative state, but is also incorrectly removing the
very necessary RTM_DELADDR when an address is deleted that was previously
notified with an RTM_NEWADDR as being in tentative dadfailed state.

Thanks
Mike

On 08/09/17 03:18, David Miller wrote:
> From: Mike Manning <mmanning@...cade.com>
> Date: Mon,  4 Sep 2017 15:52:55 +0100
> 
>> Commit f784ad3d79e5 ("ipv6: do not send RTM_DELADDR for tentative
>> addresses") incorrectly assumes that no RTM_NEWADDR are sent for
>> addresses in tentative state, as this does happen for the standard
>> IPv6 use-case of DAD failure, see the call to ipv6_ifa_notify() in
>> addconf_dad_stop(). So as a result of this change, no RTM_DELADDR is
>> sent after DAD failure for a link-local when strict DAD (accept_dad=2)
>> is configured, or on the next admin down in other cases. The absence
>> of this notification breaks backwards compatibility and causes problems
>> after DAD failure if this notification was being relied on. The
>> solution is to allow RTM_DELADDR to still be sent after DAD failure.
>>
>> Fixes: f784ad3d79e5("ipv6: do not send RTM_DELADDR for tentative addresses")
>> Signed-off-by: Mike Manning <mmanning@...cade.com>
>> Cc: Mahesh Bandewar <maheshb@...gle.com>
> 
> Mahesh, please review this patch.
>