linux-kernel - Re: [PATCH] unaligned: delete 1-byte accessors

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Message-ID: <1563750513.2898.4.camel@HansenPartnership.com>
Date:   Mon, 22 Jul 2019 08:08:33 +0900
From:   James Bottomley <James.Bottomley@...senPartnership.com>
To:     Alexey Dobriyan <adobriyan@...il.com>, akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        axboe@...nel.dk, kvalo@...eaurora.org, john.johansen@...onical.com,
        linux-arch@...r.kernel.org
Subject: Re: [PATCH] unaligned: delete 1-byte accessors

On Mon, 2019-07-22 at 00:52 +0300, Alexey Dobriyan wrote:
> Each and every 1-byte access is aligned!

The design idea of this is for parsing descriptors.  We simply chunk up
the describing structure using get_unaligned for everything.  The
reason is because a lot of these structures come with reserved areas
which we may make use of later.  If we're using get_unaligned for
everything we can simply change a u8 to a u16 in the structure
absorbing the reserved padding.  With your change now I'd have to chase
down every byte access and replace it with get_unaligned instead of
simply changing the structure.

What's the significant advantage of this change that compensates for
the problems the above causes?

James