Re: [PATCH v4] IB/hfi1: allocate dummy net_device dynamically

[Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>]

On 4/1/24 10:53 AM, Jakub Kicinski wrote:
> On Mon, 1 Apr 2024 14:53:31 +0300 Leon Romanovsky wrote:
>> On Tue, Mar 19, 2024 at 02:09:43AM -0700, Breno Leitao wrote:
>>> Embedding net_device into structures prohibits the usage of flexible
>>> arrays in the net_device structure. For more details, see the discussion
>>> at [1].
>>>
>>> Un-embed the net_device from struct hfi1_netdev_rx by converting it
>>> into a pointer. Then use the leverage alloc_netdev() to allocate the
>>> net_device object at hfi1_alloc_rx().
>>>
>>> [1] https://lore.kernel.org/all/20240229225910.79e224cf@kernel.org/
>>>
>>> Signed-off-by: Breno Leitao <leitao@debian.org>
>>> Acked-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>  
>>
>> Jakub,
>>
>> I create shared branch for you, please pull it from:
>> https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git/log/?h=remove-dummy-netdev
> 
> Did you merge it in already?
> Turned out that the use of init_dummy_netdev as a setup function
> is broken, I'm not sure how Dennis tested this :(
> We should have pinged you, sorry.

This is what I tested, Linus 6.8 tag + cherry pick + Breno patch. So if
something went in that broke it I didn't have it in my tree.

commit 311810a6d7e37d8e7537d50e26197b7f5f02f164 (linus-master)
Author: Breno Leitao <leitao@debian.org>
Date:   Wed Mar 13 03:33:10 2024 -0700

    IB/hfi1: allocate dummy net_device dynamically

    struct net_device shouldn't be embedded into any structure, instead,
    the owner should use the priv space to embed their state into net_device.

    Embedding net_device into structures prohibits the usage of flexible
    arrays in the net_device structure. For more details, see the discussion
    at [1].

    Un-embed the net_device from struct hfi1_netdev_rx by converting it
    into a pointer. Then use the leverage alloc_netdev() to allocate the
    net_device object at hfi1_alloc_rx().

    [1] https://lore.kernel.org/all/20240229225910.79e224cf@kernel.org/

    Signed-off-by: Breno Leitao <leitao@debian.org>

    ----
    PS: this diff needs d160c66cda0ac8614 ("net: Do not return value from
    init_dummy_netdev()") in order to apply and build cleanly.

commit 1e06cffe69e6519f8ede42c60f13ad3a7ddb09b7
Author: Amit Cohen <amcohen@nvidia.com>
Date:   Mon Feb 5 12:30:22 2024 +0200

    net: Do not return value from init_dummy_netdev()

    init_dummy_netdev() always returns zero and all the callers do not check
    the returned value. Set the function to not return value, as it is not
    really used today.

    Signed-off-by: Amit Cohen <amcohen@nvidia.com>
    Reviewed-by: Ido Schimmel <idosch@nvidia.com>
    Reviewed-by: Jiri Pirko <jiri@nvidia.com>
    Reviewed-by: Simon Horman <horms@kernel.org>
    Link: https://lore.kernel.org/r/20240205103022.440946-1-amcohen@nvidia.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

commit e8f897f4afef0031fe618a8e94127a0934896aba (tag: v6.8)
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun Mar 10 13:38:09 2024 -0700

    Linux 6.8