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From: Jens Axboe <axboe@kernel.dk>
To: Pavel Begunkov <asml.silence@gmail.com>,
	Stefano Garzarella <sgarzare@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Kees Cook <keescook@chromium.org>, Aleksa Sarai <asarai@suse.de>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Sargun Dhillon <sargun@sargun.me>, Jann Horn <jannh@google.com>,
	io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Jeff Moyer <jmoyer@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC v2 1/3] io_uring: use an enumeration for io_uring_register(2) opcodes
Date: Thu, 16 Jul 2020 14:51:26 -0600	[thread overview]
Message-ID: <76879432-745d-a5ca-b171-b1391b926ea2@kernel.dk> (raw)
In-Reply-To: <20326d79-fb5a-2480-e52a-e154e056171f@gmail.com>

On 7/16/20 2:47 PM, Pavel Begunkov wrote:
> On 16/07/2020 23:42, Jens Axboe wrote:
>> On 7/16/20 2:16 PM, Pavel Begunkov wrote:
>>> On 16/07/2020 15:48, Stefano Garzarella wrote:
>>>> The enumeration allows us to keep track of the last
>>>> io_uring_register(2) opcode available.
>>>>
>>>> Behaviour and opcodes names don't change.
>>>>
>>>> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
>>>> ---
>>>>  include/uapi/linux/io_uring.h | 27 ++++++++++++++++-----------
>>>>  1 file changed, 16 insertions(+), 11 deletions(-)
>>>>
>>>> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
>>>> index 7843742b8b74..efc50bd0af34 100644
>>>> --- a/include/uapi/linux/io_uring.h
>>>> +++ b/include/uapi/linux/io_uring.h
>>>> @@ -253,17 +253,22 @@ struct io_uring_params {
>>>>  /*
>>>>   * io_uring_register(2) opcodes and arguments
>>>>   */
>>>> -#define IORING_REGISTER_BUFFERS		0
>>>> -#define IORING_UNREGISTER_BUFFERS	1
>>>> -#define IORING_REGISTER_FILES		2
>>>> -#define IORING_UNREGISTER_FILES		3
>>>> -#define IORING_REGISTER_EVENTFD		4
>>>> -#define IORING_UNREGISTER_EVENTFD	5
>>>> -#define IORING_REGISTER_FILES_UPDATE	6
>>>> -#define IORING_REGISTER_EVENTFD_ASYNC	7
>>>> -#define IORING_REGISTER_PROBE		8
>>>> -#define IORING_REGISTER_PERSONALITY	9
>>>> -#define IORING_UNREGISTER_PERSONALITY	10
>>>> +enum {
>>>> +	IORING_REGISTER_BUFFERS,
>>>> +	IORING_UNREGISTER_BUFFERS,
>>>> +	IORING_REGISTER_FILES,
>>>> +	IORING_UNREGISTER_FILES,
>>>> +	IORING_REGISTER_EVENTFD,
>>>> +	IORING_UNREGISTER_EVENTFD,
>>>> +	IORING_REGISTER_FILES_UPDATE,
>>>> +	IORING_REGISTER_EVENTFD_ASYNC,
>>>> +	IORING_REGISTER_PROBE,
>>>> +	IORING_REGISTER_PERSONALITY,
>>>> +	IORING_UNREGISTER_PERSONALITY,
>>>> +
>>>> +	/* this goes last */
>>>> +	IORING_REGISTER_LAST
>>>> +};
>>>
>>> It breaks userspace API. E.g.
>>>
>>> #ifdef IORING_REGISTER_BUFFERS
>>
>> It can, yes, but we have done that in the past. In this one, for
> 
> Ok, if nobody on the userspace side cares, then better to do that
> sooner than later.
> 
> 
>> example:
>>
>> commit 9e3aa61ae3e01ce1ce6361a41ef725e1f4d1d2bf (tag: io_uring-5.5-20191212)
>> Author: Jens Axboe <axboe@kernel.dk>
>> Date:   Wed Dec 11 15:55:43 2019 -0700
>>
>>     io_uring: ensure we return -EINVAL on unknown opcod
>>
>> But it would be safer/saner to do this like we have the done the IOSQE_
>> flags.
> 
> IOSQE_ are a bitmask, but this would look peculiar
> 
> enum {
> 	__IORING_REGISTER_BUFFERS,
> 	...
> };
> define IORING_REGISTER_BUFFERS __IORING_REGISTER_BUFFERS

Yeah true of course, that won't really work for this case at all.

That said, I don't think it's a huge deal to turn it into an enum.


-- 
Jens Axboe


  reply	other threads:[~2020-07-16 20:51 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-16 12:48 [PATCH RFC v2 0/3] io_uring: add restrictions to support untrusted applications and guests Stefano Garzarella
2020-07-16 12:48 ` [PATCH RFC v2 1/3] io_uring: use an enumeration for io_uring_register(2) opcodes Stefano Garzarella
2020-07-16 20:16   ` Pavel Begunkov
2020-07-16 20:42     ` Jens Axboe
2020-07-16 20:47       ` Pavel Begunkov
2020-07-16 20:51         ` Jens Axboe [this message]
2020-07-16 21:20           ` Jens Axboe
2020-07-17  8:13             ` Stefano Garzarella
2020-07-16 12:48 ` [PATCH RFC v2 2/3] io_uring: add IOURING_REGISTER_RESTRICTIONS opcode Stefano Garzarella
2020-07-16 21:26   ` Jens Axboe
2020-07-17  8:55     ` Stefano Garzarella
2020-07-21 10:40     ` Stefano Garzarella
2020-07-21 17:11       ` Jens Axboe
2020-07-22  2:35         ` Daurnimator
2020-07-22 14:14           ` Stefano Garzarella
2020-07-22 14:29         ` Stefano Garzarella
2020-07-16 12:48 ` [PATCH RFC v2 3/3] io_uring: allow disabling rings during the creation Stefano Garzarella

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