linux-kernel - Re: [PATCH] ublk: inline __ublk_ch_uring

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Message-ID: <aLZXAExxsZAuZyeZ@fedora>
Date: Tue, 2 Sep 2025 10:31:28 +0800
From: Ming Lei <ming.lei@...hat.com>
To: Caleb Sander Mateos <csander@...estorage.com>
Cc: Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ublk: inline __ublk_ch_uring_cmd()

On Fri, Aug 08, 2025 at 09:32:50AM -0600, Caleb Sander Mateos wrote:
> ublk_ch_uring_cmd_local() is a thin wrapper around __ublk_ch_uring_cmd()
> that copies the ublksrv_io_cmd from user-mapped memory to the stack
> using READ_ONCE(). This ublksrv_io_cmd is passed by pointer to
> __ublk_ch_uring_cmd() and __ublk_ch_uring_cmd() is a large function
> unlikely to be inlined, so __ublk_ch_uring_cmd() will have to load the
> ublksrv_io_cmd fields back from the stack. Inline __ublk_ch_uring_cmd()
> into ublk_ch_uring_cmd_local() and load the ublksrv_io_cmd fields into
> local variables with READ_ONCE(). This allows the compiler to delay
> loading the fields until they are needed and choose whether to store
> them in registers or on the stack.
> 
> Signed-off-by: Caleb Sander Mateos <csander@...estorage.com>

Looks good,

Reviewed-by: Ming Lei <ming.lei@...hat.com>

Thanks,
Ming