linux-kernel - Re: [PATCH v2] block/mq-deadline: Remove redundant hctx pointer dereferencing operation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAAWJmAZi=CA3sysb5N8rLL3qUVWz1tmHSpPtFuYPmEb0F+_UOA@mail.gmail.com>
Date: Tue, 18 Nov 2025 15:24:36 +0800
From: Tao pilgrim <pilgrimtao@...il.com>
To: Christoph Hellwig <hch@...radead.org>
Cc: axboe@...nel.dk, linux-block@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Chengkaitao <chengkaitao@...inos.cn>
Subject: Re: [PATCH v2] block/mq-deadline: Remove redundant hctx pointer
 dereferencing operation

On Tue, Nov 18, 2025 at 2:08 PM Christoph Hellwig <hch@...radead.org> wrote:
>
> On Tue, Nov 18, 2025 at 09:25:39AM +0800, chengkaitao wrote:
> > From: Chengkaitao <chengkaitao@...inos.cn>
> >
> > The value of 'hctx->queue' is already stored in '*q' within
> > dd_insert_requests, we can directly reuse the result instead of
> > dereferencing hctx again in the dd_insert_request function. This
> > patch removes the redundant operation and modifies the function's
> > parameters accordingly. We can eliminate an LDR instruction.
>
> But you pass additional parameters on the stack.  Aka you're causing
> churn here with bogus arguments.

This patch replaces "struct blk_mq_hw_ctx *hctx" with "struct request_queue *q"
without introducing additional parameters. The total number of parameters for
the dd_insert_request function remains unchanged.

-- 
Yours,
Chengkaitao