From: Josef <[email protected]>
To: Jens Axboe <[email protected]>, [email protected]
Cc: [email protected]
Subject: Re: io_uring file descriptor address already in use error
Date: Wed, 26 Aug 2020 05:01:01 +0200 [thread overview]
Message-ID: <CAAss7+o5_74C3tG09Yw2KaL4B7vVg68aNf=UF-YmTaNGokSOfQ@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
> In order for the patch to be able to move ahead, we'd need to be able
> to control this behavior. Right now we rely on the file being there if
> we need to repoll, see:
>
> commit a6ba632d2c249a4390289727c07b8b55eb02a41d
> Author: Jens Axboe <[email protected]>
> Date: Fri Apr 3 11:10:14 2020 -0600
>
> io_uring: retry poll if we got woken with non-matching mask
>
> If this never happened, we would not need the file at all and we could
> make it the default behavior. But don't think that's solvable.
>
> > is there no other way around to close the file descriptor? Even if I
> > remove the poll, it doesn't work
>
> If you remove the poll it should definitely work, as nobody is holding a
> reference to it as you have nothing else in flight. Can you clarify what
> you mean here?
>
> I don't think there's another way, outside of having a poll (io_uring
> or poll(2), doesn't matter, the behavior is the same) being triggered in
> error. That doesn't happen, as mentioned if you do epoll/poll on a file
> and you close it, it won't trigger an event.
>
> > btw if understood correctly poll remove operation refers to all file
> > descriptors which arming a poll in the ring buffer right?
> > Is there a way to cancel a specific file descriptor poll?
>
> You can cancel specific requests by identifying them with their
> ->user_data. You can cancel a poll either with POLL_REMOVE or
> ASYNC_CANCEL, either one will find it. So as long as you have that, and
> it's unique, it'll only cancel that one specific request.
thanks it works, my bad, I was not aware that user_data is associated
with the poll request user_data...just need to remove my server socket
poll which binds to an address so I think this patch is not really
necessary
btw IORING_FEAT_FAST_POLL feature which arming poll for read events,
how does it work when the file descriptor(not readable yet) wants to
read(non blocking) something and I close(2) the file descriptor? I'm
guessing io_uring doesn't hold any reference to it anymore right?
---
Josef Grieb
next prev parent reply other threads:[~2020-08-26 3:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-25 15:00 io_uring file descriptor address already in use error Josef
2020-08-25 15:12 ` Jens Axboe
2020-08-25 15:17 ` Jens Axboe
2020-08-25 15:48 ` Jens Axboe
2020-08-25 16:38 ` Josef
2020-08-25 16:47 ` Jens Axboe
2020-08-26 3:01 ` Josef [this message]
2020-08-26 13:44 ` Jens Axboe
2020-08-26 18:25 ` Josef
2020-08-26 18:39 ` Jens Axboe
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