Re: [PATCH RESEND bpf-next v10 6/8] bpf: add bpf_list_is_first/last/empty kfuncs

[Eduard Zingerman]

On Tue, 2026-05-12 at 13:59 +0800, Kaitao cheng wrote:
> From: Kaitao Cheng <chengkaitao@xxxxxxxxxx>
> 
> Add three kfuncs for BPF linked list queries:
> - bpf_list_is_first(head, node): true if node is the first in the list.
> - bpf_list_is_last(head, node): true if node is the last in the list.
> - bpf_list_empty(head): true if the list has no entries.
> 
> Currently, without these kfuncs, to implement the above functionality
> it is necessary to first call bpf_list_pop_front/back to retrieve the
> first or last node before checking whether the passed-in node was the
> first or last one. After the check, the node had to be pushed back into
> the list using bpf_list_push_front/back, which was very inefficient.
> 
> Now, with the bpf_list_is_first/last/empty kfuncs, we can directly
> check whether a node is the first, last, or whether the list is empty,
> without having to first retrieve the node.
> 
> Signed-off-by: Kaitao Cheng <chengkaitao@xxxxxxxxxx>
> Reviewed-by: Emil Tsalapatis <emil@xxxxxxxxxxxxxxx>
> ---

Reviewed-by: Eduard Zingerman <eddyz87@xxxxxxxxx>

[...]