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Date: Thu, 16 Jul 2020 14:42:08 -0600
From: Jens Axboe <axboe@...nel.dk>
To: Pavel Begunkov <asml.silence@...il.com>,
Stefano Garzarella <sgarzare@...hat.com>
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>,
Kees Cook <keescook@...omium.org>, Aleksa Sarai <asarai@...e.de>,
Stefan Hajnoczi <stefanha@...hat.com>,
Christian Brauner <christian.brauner@...ntu.com>,
Sargun Dhillon <sargun@...gun.me>, Jann Horn <jannh@...gle.com>,
io-uring@...r.kernel.org, linux-fsdevel@...r.kernel.org,
Jeff Moyer <jmoyer@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC v2 1/3] io_uring: use an enumeration for
io_uring_register(2) opcodes
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@...hat.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
example:
commit 9e3aa61ae3e01ce1ce6361a41ef725e1f4d1d2bf (tag: io_uring-5.5-20191212)
Author: Jens Axboe <axboe@...nel.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.
--
Jens Axboe
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