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From: Christoph Hellwig <hch@infradead.org>
To: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
	Jiri Kosina <jikos@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>, Shuah Khan <shuah@kernel.org>,
	Dave Marchevsky <davemarchevsky@fb.com>,
	Joe Stringer <joe@cilium.io>, Jonathan Corbet <corbet@lwn.net>,
	Tero Kristo <tero.kristo@linux.intel.com>,
	linux-kernel@vger.kernel.org, linux-input@vger.kernel.org,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH bpf-next v5 00/17] Introduce eBPF support for HID devices
Date: Thu, 19 May 2022 01:10:48 -0700	[thread overview]
Message-ID: <YoX7iHddAd4FkQRQ@infradead.org> (raw)
In-Reply-To: <20220518205924.399291-1-benjamin.tissoires@redhat.com>

> The logic is the following (see also the last patch for some more
> documentation):
> - hid-bpf first preloads a BPF program in the kernel that does a few
>   things:
>    * find out which attach_btf_id are associated with our trace points
>    * adds a bpf_tail_call() BPF program that I can use to "call" any
>      other BPF program stored into a jump table
>    * monitors the releases of struct bpf_prog, and when there are no
>      other users than us, detach the bpf progs from the HID devices
> - users then declare their tracepoints and then call
>   hid_bpf_attach_prog() in a SEC("syscall") program
> - hid-bpf then calls multiple time the bpf_tail_call() program with a
>   different index in the jump table whenever there is an event coming
>   from a matching HID device

So driver abstractions like UDI are now perfectly fine as long as they
are written using a hip new VM?

This whole idea seems like a bad idea, against the Linux spirit and
now actually useful - it is totally trivial to write a new HID
driver alreay, and if it isn't in some cases we need to fix that.

So a big fat NAK to the idea of using eBPF for actual driver logic.

  parent reply	other threads:[~2022-05-19  8:11 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-18 20:59 [PATCH bpf-next v5 00/17] Introduce eBPF support for HID devices Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 01/17] bpf/btf: also allow kfunc in tracing and syscall programs Benjamin Tissoires
2022-05-21  2:34   ` Alexei Starovoitov
2022-05-18 20:59 ` [PATCH bpf-next v5 02/17] bpf/verifier: allow kfunc to return an allocated mem Benjamin Tissoires
2022-05-18 21:59   ` Kumar Kartikeya Dwivedi
2022-05-19 12:05     ` Benjamin Tissoires
2022-05-19 12:40       ` Kumar Kartikeya Dwivedi
2022-05-18 20:59 ` [PATCH bpf-next v5 03/17] bpf: prepare for more bpf syscall to be used from kernel and user space Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 04/17] libbpf: add map_get_fd_by_id and map_delete_elem in light skeleton Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 05/17] HID: core: store the unique system identifier in hid_device Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 06/17] HID: export hid_report_type to uapi Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 07/17] HID: initial BPF implementation Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 08/17] selftests/bpf: add tests for the HID-bpf initial implementation Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 09/17] HID: bpf: allocate data memory for device_event BPF programs Benjamin Tissoires
2022-05-18 23:13   ` kernel test robot
2022-05-18 20:59 ` [PATCH bpf-next v5 10/17] selftests/bpf/hid: add test to change the report size Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 11/17] HID: bpf: introduce hid_hw_request() Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 12/17] selftests/bpf: add tests for bpf_hid_hw_request Benjamin Tissoires
2022-05-18 22:20   ` Kumar Kartikeya Dwivedi
2022-05-19 12:12     ` Benjamin Tissoires
2022-05-19 12:51       ` Kumar Kartikeya Dwivedi
2022-05-19 13:13         ` Benjamin Tissoires
2022-05-19 13:44           ` Kumar Kartikeya Dwivedi
2022-05-19 15:47             ` Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 13/17] HID: bpf: allow to change the report descriptor Benjamin Tissoires
2022-05-21  2:46   ` Alexei Starovoitov
2022-05-18 20:59 ` [PATCH bpf-next v5 14/17] selftests/bpf: add report descriptor fixup tests Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 15/17] samples/bpf: add new hid_mouse example Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 16/17] selftests/bpf: Add a test for BPF_F_INSERT_HEAD Benjamin Tissoires
2022-05-18 20:59 ` [PATCH bpf-next v5 17/17] Documentation: add HID-BPF docs Benjamin Tissoires
2022-05-19  8:10 ` Christoph Hellwig [this message]
2022-05-19  8:20   ` [PATCH bpf-next v5 00/17] Introduce eBPF support for HID devices Greg KH
2022-05-19  8:38     ` Christoph Hellwig
2022-05-19 10:20       ` Benjamin Tissoires
2022-05-19 10:43         ` Toke Høiland-Jørgensen
2022-05-19 11:56           ` Benjamin Tissoires
2022-05-21  0:18             ` Alexei Starovoitov
2022-05-19 10:32       ` Greg KH
2022-05-19 11:46         ` Benjamin Tissoires
2022-05-21  2:40 ` patchwork-bot+netdevbpf
2022-05-27  7:26 ` Tero Kristo
2022-05-30 15:49   ` Benjamin Tissoires

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