netdev - Re: [PATCH net 1/2] gre: Fix IPv6 multicast route creation.

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Message-ID: <aHFEzWcTCy4vnlBB@debian>
Date: Fri, 11 Jul 2025 19:07:25 +0200
From: Guillaume Nault <gnault@...hat.com>
To: Gary Guo <gary@...yguo.net>
Cc: David Miller <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>, Eric Dumazet <edumazet@...gle.com>,
	netdev@...r.kernel.org, Simon Horman <horms@...nel.org>,
	David Ahern <dsahern@...nel.org>, Ido Schimmel <idosch@...dia.com>,
	Aiden Yang <ling@...dove.com>
Subject: Re: [PATCH net 1/2] gre: Fix IPv6 multicast route creation.

On Thu, Jul 10, 2025 at 01:57:57PM +0100, Gary Guo wrote:
> On Wed, 9 Jul 2025 16:30:10 +0200
> Guillaume Nault <gnault@...hat.com> wrote:
> 
> > Use addrconf_add_dev() instead of ipv6_find_idev() in
> > addrconf_gre_config() so that we don't just get the inet6_dev, but also
> > install the default ff00::/8 multicast route.
> > 
> > Before commit 3e6a0243ff00 ("gre: Fix again IPv6 link-local address
> > generation."), the multicast route was created at the end of the
> > function by addrconf_add_mroute(). But this code path is now only taken
> > in one particular case (gre devices not bound to a local IP address and
> > in EUI64 mode). For all other cases, the function exits early and
> > addrconf_add_mroute() is not called anymore.
> > 
> > Using addrconf_add_dev() instead of ipv6_find_idev() in
> > addrconf_gre_config(), fixes the problem as it will create the default
> > multicast route for all gre devices. This also brings
> > addrconf_gre_config() a bit closer to the normal netdevice IPv6
> > configuration code (addrconf_dev_config()).
> > 
> > Fixes: 3e6a0243ff00 ("gre: Fix again IPv6 link-local address generation.")
> > Reported-by: Aiden Yang <ling@...dove.com>
> > Closes: https://lore.kernel.org/netdev/CANR=AhRM7YHHXVxJ4DmrTNMeuEOY87K2mLmo9KMed1JMr20p6g@mail.gmail.com/
> > Reviewed-by: Gary Guo <gary@...yguo.net>
> > Tested-by: Gary Guo <gary@...yguo.net>
> > Signed-off-by: Guillaume Nault <gnault@...hat.com>
> 
> You probably also want to
> 
> Cc: stable@...r.kernel.org
> 
> so this gets picked up by the stable team after it's merged.

Yeah, I forgot that the policy had changed.
It seems that Jakub took care of it anyway.
Thanks again!

> Best,
> Gary
>