linux-kernel - Re: [PATCH] io_uring: pass struct io_tw

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Message-ID: <8c21acb0-aee5-4628-a267-a4edc85616c4@kernel.dk>
Date: Wed, 12 Feb 2025 07:33:03 -0700
From: Jens Axboe <axboe@...nel.dk>
To: Caleb Sander Mateos <csander@...estorage.com>,
 Pavel Begunkov <asml.silence@...il.com>
Cc: io-uring@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] io_uring: pass struct io_tw_state by value

On 2/11/25 2:45 PM, Caleb Sander Mateos wrote:
> 8e5b3b89ecaf ("io_uring: remove struct io_tw_state::locked") removed the
> only field of io_tw_state but kept it as a task work callback argument
> to "forc[e] users not to invoke them carelessly out of a wrong context".
> Passing the struct io_tw_state * argument adds a few instructions to all
> callers that can't inline the functions and see the argument is unused.
> 
> So pass struct io_tw_state by value instead. Since it's a 0-sized value,
> it can be passed without any instructions needed to initialize it.
> 
> Also add a comment to struct io_tw_state to explain its purpose.

This is nice, reduces the code generated. It'll conflict with the
fix that Pavel posted, but I can just mangle this one once I get
the 6.15 branch rebased on top of -rc3. No need to send a v2.

-- 
Jens Axboe