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Message-ID: <20241023040316.28273-1-kuniyu@amazon.com>
Date: Tue, 22 Oct 2024 21:03:16 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: <shaw.leon@...il.com>
CC: <davem@...emloft.net>, <dsahern@...nel.org>, <edumazet@...gle.com>,
<idosch@...dia.com>, <kuba@...nel.org>, <kuniyu@...zon.com>,
<netdev@...r.kernel.org>, <pabeni@...hat.com>
Subject: Re: [PATCH net-next 2/5] rtnetlink: Add netns_atomic flag in rtnl_link_ops
From: Xiao Liang <shaw.leon@...il.com>
Date: Wed, 23 Oct 2024 10:31:43 +0800
> Currently these two steps are needed to create a net device with
> IFLA_LINK_NETNSID attr:
>
> 1. create and setup the netdev in the link netns with
> rtnl_create_link()
> 2. move it to the target netns with dev_change_net_namespace()
IIRC, this is to send the notification in the link netns.
>
> This has some side effects, including extra ifindex allocation, ifname
> validation and link notifications in link netns.
>
> Add a netns_atomic flag, that if set to true, devices will be created in
> the target netns directly.
>
> Signed-off-by: Xiao Liang <shaw.leon@...il.com>
> ---
> include/net/rtnetlink.h | 3 +++
> net/core/rtnetlink.c | 7 ++++---
> 2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/include/net/rtnetlink.h b/include/net/rtnetlink.h
> index e0d9a8eae6b6..59594cef2272 100644
> --- a/include/net/rtnetlink.h
> +++ b/include/net/rtnetlink.h
> @@ -74,6 +74,8 @@ static inline int rtnl_msg_family(const struct nlmsghdr *nlh)
> * @srcu: Used internally
> * @kind: Identifier
> * @netns_refund: Physical device, move to init_net on netns exit
> + * @netns_atomic: Device can be created in target netns even when
> + * link-netns is different, avoiding netns change.
> * @maxtype: Highest device specific netlink attribute number
> * @policy: Netlink policy for device specific attribute validation
> * @validate: Optional validation function for netlink/changelink parameters
> @@ -115,6 +117,7 @@ struct rtnl_link_ops {
> void (*setup)(struct net_device *dev);
>
> bool netns_refund;
> + bool netns_atomic;
> unsigned int maxtype;
> const struct nla_policy *policy;
> int (*validate)(struct nlattr *tb[],
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index ff8d25acfc00..99250779d8ba 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -3679,8 +3679,9 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
> name_assign_type = NET_NAME_ENUM;
> }
>
> - dev = rtnl_create_link(link_net ? : tgt_net, ifname,
> - name_assign_type, ops, tb, extack);
> + dev = rtnl_create_link(!link_net || ops->netns_atomic ?
> + tgt_net : link_net, ifname, name_assign_type,
> + ops, tb, extack);
> if (IS_ERR(dev)) {
> err = PTR_ERR(dev);
> goto out;
> @@ -3700,7 +3701,7 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
> err = rtnl_configure_link(dev, ifm, portid, nlh);
> if (err < 0)
> goto out_unregister;
> - if (link_net) {
> + if (link_net && !ops->netns_atomic) {
> err = dev_change_net_namespace(dev, tgt_net, ifname);
> if (err < 0)
> goto out_unregister;
> --
> 2.47.0
>
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