From: Jens Axboe <axboe@kernel.dk>
To: Pavel Begunkov <asml.silence@gmail.com>, io-uring@vger.kernel.org
Cc: linux-block@vger.kernel.org, jannh@google.com
Subject: Re: [PATCH 2/3] io_uring: pass in io_kiocb to fill/add CQ handlers
Date: Thu, 7 Nov 2019 06:16:36 -0700 [thread overview]
Message-ID: <2a723bbc-f031-6d2a-ef8b-96f9a5cfc70e@kernel.dk> (raw)
In-Reply-To: <df4352ab-2670-e69f-cc92-5e72f1cd6229@gmail.com>
On 11/7/19 2:53 AM, Pavel Begunkov wrote:
>> @@ -804,8 +803,10 @@ static void io_fail_links(struct io_kiocb *req)
>> link->submit.sqe->opcode == IORING_OP_LINK_TIMEOUT) {
>> io_link_cancel_timeout(ctx, link);
>> } else {
>> - io_cqring_fill_event(ctx, link->user_data, -ECANCELED);
>> - __io_free_req(link);
>> + io_cqring_fill_event(link, -ECANCELED);
>> + /* drop both submit and complete references */
>> + io_put_req(link, NULL);
>> + io_put_req(link, NULL);
>
> io_put_req() -> ... -> io_free_req() -> io_fail_links() -> io_put_req()
>
> It shouldn't recurse further, but probably it would be better to avoid
> it at all.
Not sure how to improve that. We could do something ala:
if (refcount_sub_and_test(2, &link->refs))
__io_free_req(link);
to make it clear and more resistant against recursion.
I also think we need to put that link path out-of-line in io_free_req().
I'll make those two changes.
--
Jens Axboe
next prev parent reply other threads:[~2019-11-07 13:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 23:53 [PATCHSET v2 0/3] io_uring CQ ring backpressure Jens Axboe
2019-11-06 23:53 ` [PATCH 1/3] io_uring: make io_cqring_events() take 'ctx' as argument Jens Axboe
2019-11-06 23:53 ` [PATCH 2/3] io_uring: pass in io_kiocb to fill/add CQ handlers Jens Axboe
2019-11-07 9:53 ` Pavel Begunkov
2019-11-07 13:16 ` Jens Axboe [this message]
2019-11-06 23:53 ` [PATCH 3/3] io_uring: add support for backlogged CQ ring Jens Axboe
2019-11-07 16:00 [PATCHSET v3 0/3] io_uring CQ ring backpressure Jens Axboe
2019-11-07 16:00 ` [PATCH 2/3] io_uring: pass in io_kiocb to fill/add CQ handlers Jens Axboe
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