Re: [PATCH v2] RDMA/hns: drop dead empty check in setup_root_hem()

[Jason Gunthorpe]

On Tue, May 26, 2026 at 01:46:53PM +0800, Maoyi Xie wrote:
> setup_root_hem() reads the first entry of head->root and checks
> the returned pointer against NULL:
> 
>     root_hem = list_first_entry(&head->root,
>                                 struct hns_roce_hem_item, list);
>     if (!root_hem)
>         return -ENOMEM;
> 
> list_first_entry() never returns NULL. On an empty list it returns
> container_of(head, ..., list), a non-NULL garbage pointer that
> aliases the head. So the check is dead.
> 
> The only caller adds an entry to head.root right before invoking
> setup_root_hem():
> 
>     list_add(&root_hem->list, &head.root);
>     ret = setup_root_hem(..., &head, ...);
> 
> So head.root is guaranteed non-empty on entry. Drop the check.
> 
> Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Signed-off-by: Maoyi Xie <maoyixie.tju@xxxxxxxxx>
> ---
> v2: drop the check entirely per Jason's review, instead of
>     converting to list_first_entry_or_null() as in v1.
> v1: https://lore.kernel.org/r/20260521132045.3430906-1-maoyixie.tju@xxxxxxxxx
> 
>  drivers/infiniband/hw/hns/hns_roce_hem.c | 2 --
>  1 file changed, 2 deletions(-)

Applied to for-next, thanks

Jason