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Thu, 16 Jul 2020 13:42:09 -0700 (PDT) Subject: Re: [PATCH RFC v2 1/3] io_uring: use an enumeration for io_uring_register(2) opcodes To: Pavel Begunkov , Stefano Garzarella Cc: Alexander Viro , Kernel Hardening , Kees Cook , Aleksa Sarai , Stefan Hajnoczi , Christian Brauner , Sargun Dhillon , Jann Horn , io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org, Jeff Moyer , linux-kernel@vger.kernel.org References: <20200716124833.93667-1-sgarzare@redhat.com> <20200716124833.93667-2-sgarzare@redhat.com> From: Jens Axboe Message-ID: Date: Thu, 16 Jul 2020 14:42:08 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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 >> --- >> 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 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