Re: [patch V3 07/12] uaccess: Provide scoped masked user access regions

From: Thomas Gleixner <tglx@linutronix.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David Laight" <david.laight.linux@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"Christophe Leroy" <christophe.leroy@csgroup.eu>,
	"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"kernel test robot" <lkp@intel.com>,
	"Russell King" <linux@armlinux.org.uk>,
	linux-arm-kernel@lists.infradead.org, x86@kernel.org,
	"Madhavan Srinivasan" <maddy@linux.ibm.com>,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Nicholas Piggin" <npiggin@gmail.com>,
	linuxppc-dev@lists.ozlabs.org, "Paul Walmsley" <pjw@kernel.org>,
	"Palmer Dabbelt" <palmer@dabbelt.com>,
	linux-riscv@lists.infradead.org,
	"Heiko Carstens" <hca@linux.ibm.com>,
	"Christian Borntraeger" <borntraeger@linux.ibm.com>,
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	linux-s390@vger.kernel.org,
	"Julia Lawall" <Julia.Lawall@inria.fr>,
	"Nicolas Palix" <nicolas.palix@imag.fr>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Darren Hart" <dvhart@infradead.org>,
	"Davidlohr Bueso" <dave@stgolabs.net>,
	"André Almeida" <andrealmeid@igalia.com>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	"Christian Brauner" <brauner@kernel.org>,
	"Jan Kara" <jack@suse.cz>,
	linux-fsdevel@vger.kernel.org
Subject: Re: [patch V3 07/12] uaccess: Provide scoped masked user access regions
Date: Tue, 21 Oct 2025 17:45:56 +0200	[thread overview]
Message-ID: <871pmwz2a3.ffs@tglx> (raw)
In-Reply-To: <CAHk-=wgE-dAHPzrZ7RxwZNdqw8u-5w1HGQUWAWQ0rMDCJORfCw@mail.gmail.com>

On Tue, Oct 21 2025 at 05:06, Linus Torvalds wrote:
> On Tue, 21 Oct 2025 at 04:30, Thomas Gleixner <tglx@linutronix.de> wrote:
>>
>> On Mon, Oct 20 2025 at 19:28, David Laight wrote:
>> >
>> > (I don't like the word 'masked' at all, not sure where it came from.
>>
>> It's what Linus named it and I did not think about the name much so far.
>
> The original implementation was a mask application, so it made sense
> at the time.
>
> We could still change it since there aren't that many users, but I'm
> not sure what would be a better name...

I couldn't come up with something sensible for the architecture side.

But for the scope guards I think the simple scoped_user_$MODE_access()
is fine as for the usage site it's just a user access, no?

the scope magic resolves either to the "masked" variant or to the
regular user_access_begin() + speculation barrier depending on
architecture support. But that's under the hood an implementation detail
of the scope...() macros.

Thanks,

        tglx