linux-kernel - RE: [PATCH] nvme: Increase block size variable size to 32-bit

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Message-ID: <e203876fc20d4c7b932bbff35e8b5e1e@AcuMS.aculab.com>
Date:   Thu, 1 Jun 2023 10:28:45 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Christoph Hellwig' <hch@....de>,
        Daniel Gomez <da.gomez@...sung.com>
CC:     Keith Busch <kbusch@...nel.org>, Jens Axboe <axboe@...nel.dk>,
        "Sagi Grimberg" <sagi@...mberg.me>,
        Pankaj Raghav <p.raghav@...sung.com>,
        "mcgrof@...nel.org" <mcgrof@...nel.org>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] nvme: Increase block size variable size to 32-bit

From: Christoph Hellwig
> Sent: 31 May 2023 14:03
> 
> > +	u32 bs = 1 << ns->lba_shift;
> 
> Make that 1 a 1U so that we're not going to run into sign extension
> issues when using up all bits in the u32 :)

Not 'sign extension' but obscure integer shift/conversion issues
that really only affect 1's compliment and sign-overpunch cpu.
I'm not even sure gcc/clang support any non 2's compliment systems.

> Otherwise looks good:

Probably improves the generated code as well.

	David

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