This is the v2 of the proposal for documenting BPF kfunc lifecycle and stability. v1 of this proposal can be found in [0]. As [0] indicates, Toke has also provided several RFC proposals, the most recent of which is can be found in [1]. Much of this proposal is based on Toke's prior patches on this topic, and group discussions at BPF office hours. Anyone who participated in either prior proposals for kfunc lifecycle / stability documentation, or in BPF office-hour discussions, may feel free to submit Co-developed-by tags in place of Acked-by, Reviewed-by, etc. Changelog --------- v1 -> v2: - Move some of the main points of the arguments around. v1 underscored quite strongly that kfuncs don't have _any_ stability guarantees. While true, it may scare away users who misinterpret the implications of that to mean that things will change wildly and at any time. Reframe the general flow of the section to still be clear that no stability is guaranteed, but front-load the content that clarifies why this isn't necessarily something to be afraid of (Toke, Daniel, and others). - Add a paragraph explaining that out-of-tree BPF programs that use kfuncs are relevant to discussions surrounding whether kfuncs should be modified or removed. While the onus is on kfunc users to explicitly engage with the upstream community to let them know which kfuncs they're using and why they're useful, the added paragraph also makes it clear that the BPF community will in turn participate in upstream discussions to ensure that such users aren't equated with out-of-tree module users and outright ignored. Also make it clear that our hope is that BPF programs will be upstreamed on a more regular basis (Toke, Daniel, and others). - Remove patches that add KF_DEPRECATED flag to <linux/btf.h>. They'll remain in the documentation for now, and will be merged at a later time when it's actually a useful signal for developers (Alexei). [0]: https://lore.kernel.org/all/20230202163056.658641-1-void@xxxxxxxxxxxxx/ [1]: https://lore.kernel.org/all/20230201174449.94650-1-toke@xxxxxxxxxx/ David Vernet (1): bpf/docs: Document kfunc lifecycle / stability expectations Documentation/bpf/kfuncs.rst | 139 +++++++++++++++++++++++++++++++++-- 1 file changed, 134 insertions(+), 5 deletions(-) -- 2.39.0
