On 9/29/23 17:06, Alexei Starovoitov wrote:
For certain cases like your example above it's relatively easy to add such support, but before we do that please describe the full use case that you wanted to implement with indirect calls.
I'll likely want some sort of indirect call for nesting schedulers in sched_ext / ghost. Specifically, when we're running pick_next_task or any thread event handler (e.g. wakeup), we're picturing having a dispatch layer that picks which bpf agent to pass that off to, *and* get a response from the call. Based on that response, we could possibly call someone else.
In this scenario, there'd be a 'base layer' BPF prog that handles pick_next_task from the kernel. That base layer would choose which subprogram to query for its pick_next_task. Depending on whether or not that subprogram has a task to run, the base layer may or may not want to run some other BPF program.
I'm not sure if an indirect call is what I'm looking for here, but it sounds somewhat related. The difference might be that I'd like to call a function from a different BPF program, if that's possible.
Thanks, Barret
