Re: [PATCH bpf-next/net v1 3/5] bpf: net_sched: Make some Qdisc_ops ops mandatory

[Martin KaFai Lau <martin.lau@linux.dev>]

On 5/1/25 3:30 PM, Amery Hung wrote:
> The patch makes all currently supported Qdisc_ops (i.e., .enqueue,
> .dequeue, .init, .reser, and .destroy) mandatory.

s/reser/reset/.

> 
> Make .init, .reset and .destroy mandatory as bpf qdisc relies on prologue
> and epilogue to check attach points and correctly initialize/cleanup
> resources. The prologue/epilogue will only be generated for an struct_ops
> operator only if users implement the operator.
> 
> Make .enqueue and .dequeue mandatory as bpf qdisc infra does not provide
> a default data path.
> 
> Fixes: Fixes: c8240344956e ("bpf: net_sched: Support implementation of Qdisc_ops in bpf")
> Signed-off-by: Amery Hung <ameryhung@gmail.com>
> ---
>   net/sched/bpf_qdisc.c | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
> 
> diff --git a/net/sched/bpf_qdisc.c b/net/sched/bpf_qdisc.c
> index a8efc3ff2b7e..7ea8b54b2ab1 100644
> --- a/net/sched/bpf_qdisc.c
> +++ b/net/sched/bpf_qdisc.c
> @@ -395,6 +395,17 @@ static void bpf_qdisc_unreg(void *kdata, struct bpf_link *link)
>   	return unregister_qdisc(kdata);
>   }
>   
> +static int bpf_qdisc_validate(void *kdata)
> +{
> +	struct Qdisc_ops *ops = (struct Qdisc_ops *)kdata;
> +
> +	if (!ops->enqueue || !ops->dequeue || !ops->init ||
> +	    !ops->reset || !ops->destroy)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
>   static int Qdisc_ops__enqueue(struct sk_buff *skb__ref, struct Qdisc *sch,
>   			      struct sk_buff **to_free)
>   {
> @@ -432,6 +443,7 @@ static struct bpf_struct_ops bpf_Qdisc_ops = {
>   	.verifier_ops = &bpf_qdisc_verifier_ops,
>   	.reg = bpf_qdisc_reg,
>   	.unreg = bpf_qdisc_unreg,
> +	.validate = bpf_qdisc_validate,
>   	.init_member = bpf_qdisc_init_member,
>   	.init = bpf_qdisc_init,
>   	.name = "Qdisc_ops",