On Wed, Apr 05, 2023 at 02:42:34AM +0200, Kumar Kartikeya Dwivedi wrote:
> @@ -759,6 +759,8 @@ BPF_CALL_4(bpf_loop, u32, nr_loops, void *, callback_fn, void *, callback_ctx,
>
> for (i = 0; i < nr_loops; i++) {
> ret = callback((u64)i, (u64)(long)callback_ctx, 0, 0, 0);
> + if (bpf_get_exception())
> + return -EJUKEBOX;
This is too slow.
We cannot afford a call and conditional here.
Some time ago folks tried bpf_loop() and went back to bounded loop, because
the overhead of indirect call was not acceptable.
After that we've added inlining of bpf_loop() to make overhead to the minimum.
With prog->aux->exception[] approach it might be ok-ish,
but my preference would be to disallow throw in callbacks.
timer cb, rbtree_add cb are typically small.
bpf_loop cb can be big, but we have open coded iterators now.
So disabling asserts in cb-s is probably acceptable trade-off.
The choice of error name is odd, tbh.
