On Tue, Oct 22, 2024 at 2:43 PM Yonghong Song <yonghong.song@xxxxxxxxx> wrote:
>
> To handle a subprog may be used in more than one
> subtree (subprog 0 tree or async tree), I need to
> add a 'visited' field to bpf_subprog_info.
> I think this should work.
This is getting quite complicated.
But looks like we have even bigger problem:
SEC("lsm/...")
int BPF_PROG(...)
{
volatile char buf[..];
buf[..] =
}
The approach to have per-prog per-cpu priv stack
doesn't work for the above.
Sleepable and non-sleepable LSM progs are preemptible.
Multiple tasks can be running the same program on the same cpu
preempting each other.
The priv stack of this prog will be corrupted.
Maybe it won't be an issue for sched-ext prog
attached to a cgroup, but it feels fragile for bpf infra
to rely on implementation detail of another subsystem.
We probably need to go back to the drawing board.
