From: Jann Horn <[email protected]>
To: Jens Axboe <[email protected]>
Cc: io-uring <[email protected]>
Subject: Re: [PATCH] io_uring: use TWA_SIGNAL for task_work related to eventfd
Date: Fri, 7 Aug 2020 03:00:17 +0200 [thread overview]
Message-ID: <CAG48ez0QE3+a1Gb8ovEv_54wG-HA=Ph7fM4MT8EU8Exti0c_SQ@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
On Fri, Aug 7, 2020 at 1:57 AM Jens Axboe <[email protected]> wrote:
> An earlier commit:
>
> b7db41c9e03b ("io_uring: fix regression with always ignoring signals in io_cqring_wait()")
>
> ensured that we didn't get stuck waiting for eventfd reads when it's
> registered with the io_uring ring for event notification, but that didn't
> cover the general case of waiting on eventfd and having that dependency
> between io_uring and eventfd.
>
> Ensure that we use signaled notification for anything related to eventfd.
[...]
> @@ -1720,7 +1720,7 @@ static int io_req_task_work_add(struct io_kiocb *req, struct callback_head *cb)
> */
> if (ctx->flags & IORING_SETUP_SQPOLL)
> notify = 0;
> - else if (ctx->cq_ev_fd)
> + else if (ctx->cq_ev_fd || (req->file && eventfd_file(req->file)))
> notify = TWA_SIGNAL;
Is the idea here that you want "polling an eventfd" to have different
UAPI semantics compared to e.g. "polling a pipe"? Or is there
something in-kernel that makes eventfds special?
next prev parent reply other threads:[~2020-08-07 1:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-06 23:57 [PATCH] io_uring: use TWA_SIGNAL for task_work related to eventfd Jens Axboe
2020-08-07 1:00 ` Jann Horn [this message]
2020-08-07 1:10 ` Jens Axboe
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