linux-kernel - Re: [PATCH] io_uring: remove wait loop spurious wakeups

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Message-ID: <e11a0716-eb18-4ce3-9902-3247beafe65a@kernel.dk>
Date:   Mon, 7 Oct 2019 21:16:12 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     "Pavel Begunkov (Silence)" <asml.silence@...il.com>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] io_uring: remove wait loop spurious wakeups

On 10/7/19 5:18 PM, Pavel Begunkov (Silence) wrote:
> From: Pavel Begunkov <asml.silence@...il.com>
> 
> Any changes interesting to tasks waiting in io_cqring_wait() are
> commited with io_cqring_ev_posted(). However, io_ring_drop_ctx_refs()
> also tries to do that but with no reason, that means spurious wakeups
> every io_free_req() and io_uring_enter().
> 
> Just use percpu_ref_put() instead.

Looks good, this is a leftover from when the ctx teardown used
the waitqueue as well.

-- 
Jens Axboe