linux-kernel - Re: [PATCH] io_uring: Redefined the meaning of io_alloc_async

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Message-ID: <7e8c910f-4938-01c2-ac38-7ce89236cec1@kernel.dk>
Date:   Mon, 10 Jul 2023 11:02:21 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Gabriel Krisman Bertazi <krisman@...e.de>,
        Lu Hongfei <luhongfei@...o.com>
Cc:     Pavel Begunkov <asml.silence@...il.com>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org, opensource.kernel@...o.com
Subject: Re: [PATCH] io_uring: Redefined the meaning of io_alloc_async_data's
 return value

On 7/10/23 10:58?AM, Gabriel Krisman Bertazi wrote:
> Lu Hongfei <luhongfei@...o.com> writes:
> 
>> Usually, successful memory allocation returns true and failure returns false,
>> which is more in line with the intuitive perception of most people. So it
>> is necessary to redefine the meaning of io_alloc_async_data's return value.
>>
>> This could enhance the readability of the code and reduce the possibility
>> of confusion.
> 
> just want to say, this is the kind of patch that causes bugs in
> downstream kernels.  It is not fixing anything, and when we backport a
> future bugfix around it, it is easy to miss it and slightly break the
> semantics.

Exactly! This is also why I'm not a fan of patches like this, and was
not intending to apply it.

> That's my downstream problem, of course. But at least it would be good

Strictly speaking it is, but I think we have a responsibility to not
have core bits be different upstream "just because". IOW, making it
harder to introduce problems when backporting.

And fwiw, I'm not sure I agree on the idiomatic part of it. Lots of
functions return 0 for success and non-zero for an error. It's a bit odd
as this one is a bool, but I'm pretty sure it used to return an actual
error and this is why it looks the way it currently does.

-- 
Jens Axboe