Re: [PATCH v5 1/4] RDMA/nldev: Add dellink function pointer

["Yanjun.Zhu" <yanjun.zhu@linux.dev>]

On 3/11/26 3:01 PM, Yanjun.Zhu wrote:
>
> On 3/11/26 1:54 AM, Leon Romanovsky wrote:
>> On Tue, Mar 10, 2026 at 06:58:00PM -0700, Yanjun.Zhu wrote:
>>> On 3/10/26 12:01 PM, Leon Romanovsky wrote:
>>>> It is an RXE‑specific description, but you are adding code to the 
>>>> general
>>>> nldev path. Please clarify that this behavior applies only to RXE, and
>>>> include examples showing when and how it is invoked. In particular, 
>>>> explain
>>>> how the socket is cleaned up if delink is not called.
>>> Hi, Leon
>>>
>>> You are correct that this logic should be driver-specific. I will 
>>> add an
>>> explicit check for RDMA_DRIVER_RXE in the nldev path to ensure this 
>>> behavior
>>> is strictly scoped to RXE and does not impact other drivers (like 
>>> iWARP).
>> No, you don't need this driver_id check, because iWARP doesn't have 
>> link_ops->dellink,
>> but you should document the rationale and how it is triggered for RXE.
>>
>> Thanks
>
> Hi, Leaon

Sorry. The name should be Leon. My bad.

Zhu Yanjun

>
> Got it. The commit log explains how the netdev_notifier mechanism is 
> used to clean up the related resources.
>
> In the source code, additional comments have been added to explain how 
> the dellink operation for rxe is triggered. For iWARP, this change 
> should not make any difference because iWARP does not implement the 
> dellink function.
>
> The commit is shown below. Please take a look and share your comments. 
> If you agree, I will send out the latest commits out very soon.
>
> From c05038dcdf69c5985837736a8926ba76d9f3e8e4 Mon Sep 17 00:00:00 2001
> From: Zhu Yanjun <yanjun.zhu@linux.dev>
> Date: Fri, 23 Sep 2022 16:52:45 +0000
> Subject: [PATCH 1/1] RDMA/nldev: Add dellink function pointer
>
> The newlink function pointer was previously added to support
> dynamic RDMA link creation. In the RXE driver, this path creates
> a transport socket listening on port 4791. Consequently, a dellink
> function pointer is required to ensure these sockets are properly
> closed when a user administratively removes a link via rdma link
> delete <dev>.
>
> Furthermore, RXE does not rely solely on this nldev path for resource
> management. It also monitors the underlying net_device state via a
> registered netdev_notifier. The rxe_net_event callback serves as a
> fallback mechanism to ensure that transport sockets are forcibly closed
> and all resources are released even if dellink is not explicitly called
> (e.g., if the parent NIC interface is removed or the driver is forcefully
> unloaded).
>
> Reviewed-by: David Ahern <dsahern@kernel.org>
> Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
> ---
>  drivers/infiniband/core/nldev.c | 12 ++++++++++++
>  include/rdma/rdma_netlink.h     |  2 ++
>  2 files changed, 14 insertions(+)
>
> diff --git a/drivers/infiniband/core/nldev.c 
> b/drivers/infiniband/core/nldev.c
> index 2220a2dfab24..34f5faf80d9c 100644
> --- a/drivers/infiniband/core/nldev.c
> +++ b/drivers/infiniband/core/nldev.c
> @@ -1824,6 +1824,18 @@ static int nldev_dellink(struct sk_buff *skb, 
> struct nlmsghdr *nlh,
>          return -EINVAL;
>      }
>
> +    /*
> +     * This path is triggered by the 'rdma link delete' 
> administrative command.
> +     * For Soft-RoCE (RXE), we ensure that transport sockets are 
> closed here.
> +     * Note: iWARP driver does not implement .dellink, so this logic is
> +     * implicitly scoped to driver supporting dynamic link deletion 
> like RXE.
> +     */
> +    if (device->link_ops && device->link_ops->dellink) {
> +        err = device->link_ops->dellink(device);
> +        if (err)
> +            return err;
> +    }
> +
>      ib_unregister_device_and_put(device);
>      return 0;
>  }
> diff --git a/include/rdma/rdma_netlink.h b/include/rdma/rdma_netlink.h
> index 326deaf56d5d..2fd1358ea57d 100644
> --- a/include/rdma/rdma_netlink.h
> +++ b/include/rdma/rdma_netlink.h
> @@ -5,6 +5,7 @@
>
>  #include <linux/netlink.h>
>  #include <uapi/rdma/rdma_netlink.h>
> +#include <rdma/ib_verbs.h>
>
>  struct ib_device;
>
> @@ -126,6 +127,7 @@ struct rdma_link_ops {
>      struct list_head list;
>      const char *type;
>      int (*newlink)(const char *ibdev_name, struct net_device *ndev);
> +    int (*dellink)(struct ib_device *dev);
>  };
>
>  void rdma_link_register(struct rdma_link_ops *ops);