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Date:   Tue, 16 Aug 2022 10:09:41 -0500
From:   David Vernet <void@manifault.com>
To:     Hao Luo <haoluo@google.com>
Cc:     bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
        andrii@kernel.org, john.fastabend@gmail.com, martin.lau@linux.dev,
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        jolsa@kernel.org, tj@kernel.org, joannelkoong@gmail.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/5] bpf: Add user-space-publisher ringbuffer map type
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On Mon, Aug 15, 2022 at 02:13:13PM -0700, Hao Luo wrote:
> >
> > Iters allow userspace to kick the kernel, but IMO they're meant to enable
> > data extraction from the kernel, and dumping kernel data into user-space.
> 
> Not necessarily extracting data and dumping data. It could be used to
> do operations on a set of objects, the operation could be
> notification. Iterating and notifying are orthogonal IMHO.
> 
> > What I'm proposing is a more generalizable way of driving logic in the
> > kernel from user-space.
> > Does that make sense? Looking forward to hearing your thoughts.
> 
> Yes, sort of. I see the difference between iter and the proposed
> interface. But I am not clear about the motivation of a new APis for
> kicking callbacks from userspace. I guess maybe it will become clear,
> when you publish a concerte RFC of that interface and integrates with
> your userspace publisher.

Fair enough -- let me remove this from the cover letter in future
versions of the patch-set. To your point, there's probably little to be
gained in debating the merits of adding such APIs until there's a
concrete use-case.

Thanks,
David