From: Xiao Liang <shaw.leon@xxxxxxxxx> Date: Wed, 19 Feb 2025 20:50:28 +0800 > There are 4 net namespaces involved when creating links: > > - source netns - where the netlink socket resides, > - target netns - where to put the device being created, > - link netns - netns associated with the device (backend), > - peer netns - netns of peer device. > > Currently, two nets are passed to newlink() callback - "src_net" > parameter and "dev_net" (implicitly in net_device). They are set as > follows, depending on netlink attributes in the request. > > +------------+-------------------+---------+---------+ > | peer netns | IFLA_LINK_NETNSID | src_net | dev_net | > +------------+-------------------+---------+---------+ > | | absent | source | target | > | absent +-------------------+---------+---------+ > | | present | link | link | > +------------+-------------------+---------+---------+ > | | absent | peer | target | > | present +-------------------+---------+---------+ > | | present | peer | link | > +------------+-------------------+---------+---------+ > > When IFLA_LINK_NETNSID is present, the device is created in link netns > first and then moved to target netns. This has some side effects, > including extra ifindex allocation, ifname validation and link events. > These could be avoided if we create it in target netns from > the beginning. > > On the other hand, the meaning of src_net parameter is ambiguous. It > varies depending on how parameters are passed. It is the effective > link (or peer netns) by design, but some drivers ignore it and use > dev_net instead. > > To provide more netns context for drivers, this patch packs existing > newlink() parameters, along with the source netns, link netns and peer > netns, into a struct. The old "src_net" is renamed to "net" to avoid > confusion with real source netns, and will be deprecated later. The use > of src_net are converted to params->net trivially. > > Signed-off-by: Xiao Liang <shaw.leon@xxxxxxxxx> Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
