linux-kernel - Re: [git pull] d

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Message-ID: <CAHk-=whtfm7wKucbsT7=qSvtt7YZcQNmgn_cj3+h__1w7d_0WQ@mail.gmail.com>
Date: Mon, 27 Jan 2025 17:27:08 -0800
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: Sasha Levin <sashal@...nel.org>, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [git pull] d_revalidate pile

On Mon, 27 Jan 2025 at 17:21, Al Viro <viro@...iv.linux.org.uk> wrote:
>
> Umm...  On some architectures it does, but mostly that's the ones
> where unaligned word loads are costly.  Which target do you have
> in mind?

I was more thinking that we could just make the fallback case be a 'memcmp()'.

It's not like this particular place matters - as you say, that
byte-at-a-time code is only used on architectures that don't enable
the dcache word-at-a-time code (that requires the special "do loads
that can fault" zeropad helper), but we've had some other places where
we'd worry about the string length.

Look at d_path() for another example. That copy_from_kernel_nofault()
in prepend_copy()...

             Linus