Hi Martin,
Thank you for your reply!
On 17/05/2025 00:34, Martin KaFai Lau wrote:
On 3/20/25 10:48 AM, Matthieu Baerts (NGI0) wrote:
(...)
@BPF maintainers: we would like to allow this new mptcp_subflow bpf_iter to be used with struct_ops, but only with the two new ones we are going to introduce that are specific to MPTCP, and with not others struct_ops (TCP CC, sched_ext, etc.). We are not sure how to do that. By chance, do you have examples or doc you could point to us to have this restriction in place, please?
The bpf_qdisc.c has done that. Take a look at the "bpf_qdisc_kfunc_filter()".
It is in net-next and bpf-next/net.
Many thanks for the pointer! I see, some operations have specific kfunc, similar to our needs!
Also, for one of the two future MPTCP struct_ops, not all callbacks should be allowed to use this new bpf_iter, because they are called from different contexts. How can we ensure such callbacks from a struct_ops cannot call mptcp_subflow bpf_iter without adding new dedicated checks looking if some locks are held for all callbacks? We understood that they wanted to have something similar with sched_ext, but we are not sure if this code is ready nor if it is going to be accepted.
Same. Take a look at "bpf_qdisc_kfunc_filter()".
Excellent, thank you, we will look at that!
Cheers, Matt