linux-kernel - Re: [PATCH] nvme-pci: deduplicate empty request list checks in nvme_queue

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Message-ID: <CADUfDZosKsY3TBwPRoEvOCTErcaC3HcR3ChHj=io+=m_EPqX+Q@mail.gmail.com>
Date: Wed, 19 Nov 2025 08:01:30 -0800
From: Caleb Sander Mateos <csander@...estorage.com>
To: Christoph Hellwig <hch@....de>
Cc: Keith Busch <kbusch@...nel.org>, Jens Axboe <axboe@...nel.dk>, Sagi Grimberg <sagi@...mberg.me>, 
	linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nvme-pci: deduplicate empty request list checks in nvme_queue_rqs()

On Tue, Nov 18, 2025 at 9:48 PM Christoph Hellwig <hch@....de> wrote:
>
> On Tue, Nov 18, 2025 at 07:17:00PM -0700, Caleb Sander Mateos wrote:
> > nvme_queue_rqs() checks that nvmeq is non-NULL before calling
> > nvme_submit_cmds() and nvme_submit_cmds() checks that submit_list is
> > non-empty before doing anything. A NULL nvmeq means no requests were
> > processed from the rqlist in nvme_queue_rqs() since the last call to
> > nvme_submit_cmds(), which implies submit_list is empty. So just check
> > that submit_list is non-empty before calling nvme_submit_cmds() and drop
> > the check for NULL nvmeq.
>
> What is the rationale for this?  I had a hard time understanding the
> logic in the new version, so I don't think this helps with readability
> at least.

Just trying to avoid some branches. But if you prefer the current
version, that's fine.

Best,
Caleb