io-uring.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>, Hao Xu <haoxu@linux.alibaba.com>
Cc: io-uring@vger.kernel.org, Joseph Qi <joseph.qi@linux.alibaba.com>
Subject: Re: [PATCH 6/6] io_uring: enable multishot mode for accept
Date: Sat, 4 Sep 2021 23:46:01 +0100	[thread overview]
Message-ID: <701e50f5-2444-5b56-749b-1c1affc26ce9@gmail.com> (raw)
In-Reply-To: <c61bfb5a-036d-43be-e896-239b1c8ca1c3@kernel.dk>

On 9/4/21 7:40 PM, Jens Axboe wrote:
> On 9/4/21 9:34 AM, Hao Xu wrote:
>> 在 2021/9/4 上午12:29, Jens Axboe 写道:
>>> On 9/3/21 5:00 AM, Hao Xu wrote:
>>>> Update io_accept_prep() to enable multishot mode for accept operation.
>>>>
>>>> Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
>>>> ---
>>>>   fs/io_uring.c | 14 ++++++++++++--
>>>>   1 file changed, 12 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>>>> index eb81d37dce78..34612646ae3c 100644
>>>> --- a/fs/io_uring.c
>>>> +++ b/fs/io_uring.c
>>>> @@ -4861,6 +4861,7 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
>>>>   static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>>>>   {
>>>>   	struct io_accept *accept = &req->accept;
>>>> +	bool is_multishot;
>>>>   
>>>>   	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
>>>>   		return -EINVAL;
>>>> @@ -4872,14 +4873,23 @@ static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>>>>   	accept->flags = READ_ONCE(sqe->accept_flags);
>>>>   	accept->nofile = rlimit(RLIMIT_NOFILE);
>>>>   
>>>> +	is_multishot = accept->flags & IORING_ACCEPT_MULTISHOT;
>>>> +	if (is_multishot && (req->flags & REQ_F_FORCE_ASYNC))
>>>> +		return -EINVAL;
>>>
>>> I like the idea itself as I think it makes a lot of sense to just have
>>> an accept sitting there and generating multiple CQEs, but I'm a bit
>>> puzzled by how you pass it in. accept->flags is the accept4(2) flags,
>>> which can currently be:
>>>
>>> SOCK_NONBLOCK
>>> SOCK_CLOEXEC
>>>
>>> While there's not any overlap here, that is mostly by chance I think. A
>>> cleaner separation is needed here, what happens if some other accept4(2)
>>> flag is enabled and it just happens to be the same as
>>> IORING_ACCEPT_MULTISHOT?
>> Make sense, how about a new IOSQE flag, I saw not many
>> entries left there.
> 
> Not quite sure what the best approach would be... The mshot flag only
> makes sense for a few request types, so a bit of a shame to have to
> waste an IOSQE flag on it. Especially when the flags otherwise passed in
> are so sparse, there's plenty of bits there.
> 
> Hence while it may not be the prettiest, perhaps using accept->flags is
> ok and we just need some careful code to ensure that we never have any
> overlap.

Or we can alias with some of the almost-never-used fields like
->ioprio or ->buf_index.

> Probably best to solve that issue in include/linux/net.h, ala:
> 
> /* Flags for socket, socketpair, accept4 */
> #define SOCK_CLOEXEC	O_CLOEXEC
> #ifndef SOCK_NONBLOCK
> #define SOCK_NONBLOCK	O_NONBLOCK
> #endif
> 
> /*
>  * Only used for io_uring accept4, and deliberately chosen to overlap
>  * with the O_* file bits for read/write mode so we won't risk overlap
>  * other flags added for socket/socketpair/accept4 use in the future.
>  */
> #define SOCK_URING_MULTISHOT	00000001
> 
> which should be OK, as these overlap with the O_* filespace and the
> read/write bits are at the start of that space.
> 
> Should be done as a prep patch and sent out to netdev as well, so we can
> get their sign-off on this "hack". If we can get that done, then we have
> our flag and we can just stuff it in accept->flags as long as we clear
> it before calling into accept from io_uring.
> 

-- 
Pavel Begunkov

  reply	other threads:[~2021-09-04 22:46 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-03 11:00 [RFC 0/6] fast poll multishot mode Hao Xu
2021-09-03 11:00 ` [PATCH 1/6] io_uring: enhance flush completion logic Hao Xu
2021-09-03 11:42   ` Pavel Begunkov
2021-09-03 12:08     ` Hao Xu
2021-09-03 12:27       ` Pavel Begunkov
2021-09-03 13:38         ` Hao Xu
2021-09-17 18:49           ` Hao Xu
2021-09-03 11:00 ` [PATCH 2/6] io_uring: add IORING_ACCEPT_MULTISHOT for accept Hao Xu
2021-09-03 11:00 ` [PATCH 3/6] io_uring: add REQ_F_APOLL_MULTISHOT for requests Hao Xu
2021-09-03 11:00 ` [PATCH 4/6] io_uring: let fast poll support multishot Hao Xu
2021-09-06 15:56   ` Pavel Begunkov
2021-09-06 17:40     ` Hao Xu
2021-09-06 19:09       ` Pavel Begunkov
2021-09-07  6:38         ` Hao Xu
2021-09-06 19:04   ` Pavel Begunkov
2021-09-07  6:48     ` Hao Xu
2021-09-08 11:21       ` Hao Xu
2021-09-08 12:03         ` Pavel Begunkov
2021-09-08 13:13           ` Pavel Begunkov
2021-09-09  7:01           ` Hao Xu
2021-09-09  8:29             ` Hao Xu
2021-09-11 10:49               ` Pavel Begunkov
2021-09-11 20:19                 ` Hao Xu
2021-09-03 11:00 ` [PATCH 5/6] io_uring: implement multishot mode for accept Hao Xu
2021-09-04 22:39   ` Pavel Begunkov
2021-09-04 22:40     ` Pavel Begunkov
2021-09-06 15:34       ` Pavel Begunkov
2021-09-03 11:00 ` [PATCH 6/6] io_uring: enable " Hao Xu
2021-09-03 16:29   ` Jens Axboe
2021-09-04 15:34     ` Hao Xu
2021-09-04 18:40       ` Jens Axboe
2021-09-04 22:46         ` Pavel Begunkov [this message]
2021-09-05  7:29           ` Hao Xu
2021-09-05 19:44           ` Jens Axboe
2021-09-06  8:26             ` Hao Xu
2021-09-06  8:28               ` Hao Xu
2021-09-06 13:24               ` Jens Axboe
2021-09-06 12:35             ` Hao Xu
2021-09-06 13:31               ` Jens Axboe
2021-09-06 15:00                 ` Hao Xu
2021-09-06 15:32               ` Pavel Begunkov
2021-09-06 16:42                 ` Jens Axboe
2021-09-04 22:43   ` Pavel Begunkov
2021-09-05  6:25     ` Hao Xu
2021-09-05  8:27       ` Pavel Begunkov
2021-09-03 11:02 ` [RFC 0/6] fast poll multishot mode Hao Xu

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=701e50f5-2444-5b56-749b-1c1affc26ce9@gmail.com \
    --to=asml.silence@gmail.com \
    --cc=axboe@kernel.dk \
    --cc=haoxu@linux.alibaba.com \
    --cc=io-uring@vger.kernel.org \
    --cc=joseph.qi@linux.alibaba.com \
    --subject='Re: [PATCH 6/6] io_uring: enable multishot mode for accept' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).