Re: [PATCH 3/5] bpf: Add bpf_user_ringbuf_drain() helper

[David Vernet]

On Thu, Aug 11, 2022 at 04:22:43PM -0700, Andrii Nakryiko wrote:
> On Mon, Aug 8, 2022 at 8:54 AM David Vernet <void@xxxxxxxxxxxxx> wrote:
> >
> > Now that we have a BPF_MAP_TYPE_USER_RINGBUF map type, we need to add a
> > helper function that allows BPF programs to drain samples from the ring
> > buffer, and invoke a callback for each. This patch adds a new
> > bpf_user_ringbuf_drain() helper that provides this abstraction.
> >
> > In order to support this, we needed to also add a new PTR_TO_DYNPTR
> > register type to reflect a dynptr that was allocated by a helper function
> > and passed to a BPF program. The verifier currently only supports
> > PTR_TO_DYNPTR registers that are also DYNPTR_TYPE_LOCAL and MEM_ALLOC.
> 
> This commit message is a bit too laconic. There is a lot of
> implications of various parts of this patch, it would be great to
> highlight most important ones. Please consider elaborating a bit more.

Not a problem, I'll do this in v3.