linux-kernel - Re: [PATCH REBASE v2 0/5] return nxt propagation within io-wq ctx

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Message-ID: <5b366775-6d00-3353-995f-d284d78e9a4e@kernel.dk>
Date:   Sat, 29 Feb 2020 12:00:12 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Pavel Begunkov <asml.silence@...il.com>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH REBASE v2 0/5] return nxt propagation within io-wq ctx

On 2/29/20 11:44 AM, Pavel Begunkov wrote:
> On 29/02/2020 02:37, Pavel Begunkov wrote:
>> After io_put_req_find_next() was patched, handlers no more return
>> next work, but enqueue them through io_queue_async_work() (mostly
>> by io_put_work() -> io_put_req()). The patchset fixes that.
>>
>> Patches 1-2 clean up and removes all futile attempts to get nxt from
>> the opcode handlers. The 3rd one moves all this propagation idea into
>> work->put_work(). And the rest ones are small clean up on top.
> 
> And now I'm hesitant about the approach. It works fine, but I want to
> remove a lot of excessive locking from io-wq, and it'll be in the way.
> Ignore this, I'll try something else
> 
> The question is whether there was a problem with io_req_find_next() in
> the first place... It was stealing @nxt, when it already completed a
> request and were synchronous to the submission ref holder, thus it
> should have been fine.

There was only a problem with it if we have multiple calls of
io_put_req_find_next(), so it was a bit fragile. That was the only
issue, but that's big enough imho.

I'll ignore this series for now, you can always rebase on top of the
other stuff if you want to.

-- 
Jens Axboe