Re: [RFC PATCH bpf-next] bpf: Introduce bpf_timer

On Thu, May 20, 2021 at 11:55 AM Alexei Starovoitov
[off-list ref] wrote:

From: Alexei Starovoitov <ast@kernel.org>

Introduce 'struct bpf_timer' that can be embedded in most BPF map types
and helpers to operate on it:
long bpf_timer_init(struct bpf_timer *timer, void *callback, int flags)
long bpf_timer_mod(struct bpf_timer *timer, u64 msecs)
long bpf_timer_del(struct bpf_timer *timer)

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
This is work in progress, but gives an idea on how API will look.

Forgot to mention the todo list:
- restrict to cap_bpf
- kfree bpf_timer_list
- verifier btf checks
- restrict to array, hash, lru, lpm. per-cpu maps cannot be supported.
- safe interaction with lookup/update/delete operations and iterator
- relax the 'first field only' requirement to allow bpf_timerr in global data.
  kinda without a map.
- check prog_rdonly, frozen, mmaped flags
- decide on a return value from the timer callback
- more tests