Re: [for-rc] RDMA/core: Make sure the netdev is not already associated

[Jason Gunthorpe <jgg@ziepe.ca>]

On Mon, Dec 12, 2022 at 11:22:40AM +0200, Kamal Heib wrote:
> Make sure that the requested net_device is not already associated with
> an ib_device before trying to create a new ib_device that will be
> associated with the same net_device, this is needed to avoid creating
> siw and rxe devices that will be associated with the same net_device.
> 
> Fixes: 3856ec4b93c9 ("RDMA/core: Add RDMA_NLDEV_CMD_NEWLINK/DELLINK support")
> Signed-off-by: Kamal Heib <kheib@redhat.com>
> ---
>  drivers/infiniband/core/nldev.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c
> index a981ac2f0975..376c9e158556 100644
> --- a/drivers/infiniband/core/nldev.c
> +++ b/drivers/infiniband/core/nldev.c
> @@ -1696,6 +1696,7 @@ static int nldev_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
>  	const struct rdma_link_ops *ops;
>  	char ndev_name[IFNAMSIZ];
>  	struct net_device *ndev;
> +	struct ib_device *ibdev;
>  	char type[IFNAMSIZ];
>  	int err;
>  
> @@ -1718,6 +1719,12 @@ static int nldev_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
>  	if (!ndev)
>  		return -ENODEV;
>  
> +	ibdev = ib_device_get_by_netdev(ndev, RDMA_DRIVER_UNKNOWN);
> +	if (ibdev) {
> +		ib_device_put(ibdev);
> +		return -EINVAL;
> +	}

This is racy

What is wrong with creating two IB devices on top of the same net device?

Jason