From: David Laight <david.laight.linux@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Thomas Gleixner" <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Darren Hart" <dvhart@infradead.org>,
"Davidlohr Bueso" <dave@stgolabs.net>,
"André Almeida" <andrealmeid@igalia.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>,
"Christophe Leroy" <christophe.leroy@csgroup.eu>,
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>,
"Sven Schnelle" <svens@linux.ibm.com>,
linux-s390@vger.kernel.org,
"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Julia Lawall" <Julia.Lawall@inria.fr>,
"Nicolas Palix" <nicolas.palix@imag.fr>,
"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 V4 10/12] futex: Convert to scoped user access
Date: Thu, 23 Oct 2025 22:14:50 +0100 [thread overview]
Message-ID: <20251023221450.1303003d@pumpkin> (raw)
In-Reply-To: <CAHk-=wjoQvKpfB4X0ftqM0P0kzaZxor7C1JBC5PrLPY-ca=fnA@mail.gmail.com>
On Thu, 23 Oct 2025 09:26:12 -1000
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Thu, 23 Oct 2025 at 08:44, Thomas Gleixner <tglx@linutronix.de> wrote:
> >
> > But as you said out-of-line function call it occured to me that these
> > helpers might be just named get/put_user_inline(). Hmm?
>
> Yeah, with a comment that clearly says "you need to have actual
> performance numbers for why this needs to be inlined" for people to
> use it.
Avoiding an extra clac/stac pair for two accesses might be enough.
But for a single access it might be hard to justify.
(Even if 'return' instructions are horribly painful.
Although anyone chasing performance is probably using a local system
and just disables all that 'stuff'.)
>
> Linus
next prev parent reply other threads:[~2025-10-23 21:15 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-22 12:49 [patch V4 00/12] uaccess: Provide and use scopes for user access Thomas Gleixner
2025-10-22 12:49 ` [patch V4 01/12] ARM: uaccess: Implement missing __get_user_asm_dword() Thomas Gleixner
2025-10-22 12:49 ` [patch V4 02/12] uaccess: Provide ASM GOTO safe wrappers for unsafe_*_user() Thomas Gleixner
2025-10-22 12:49 ` [patch V4 03/12] x86/uaccess: Use unsafe wrappers for ASM GOTO Thomas Gleixner
2025-10-22 12:49 ` [patch V4 04/12] powerpc/uaccess: " Thomas Gleixner
2025-10-22 12:49 ` [patch V4 05/12] riscv/uaccess: " Thomas Gleixner
2025-10-22 12:49 ` [patch V4 06/12] s390/uaccess: " Thomas Gleixner
2025-10-22 15:00 ` Heiko Carstens
2025-10-22 12:49 ` [patch V4 07/12] uaccess: Provide scoped user access regions Thomas Gleixner
2025-10-22 14:20 ` David Laight
2025-10-22 14:23 ` Peter Zijlstra
2025-10-22 12:49 ` [patch V4 08/12] uaccess: Provide put/get_user_scoped() Thomas Gleixner
2025-10-22 12:49 ` [patch V4 09/12] [RFC] coccinelle: misc: Add scoped_$MODE_access() checker script Thomas Gleixner
2025-10-22 12:49 ` [patch V4 10/12] futex: Convert to scoped user access Thomas Gleixner
2025-10-22 15:16 ` Linus Torvalds
2025-10-23 18:44 ` Thomas Gleixner
2025-10-23 19:26 ` Linus Torvalds
2025-10-23 21:14 ` David Laight [this message]
2025-10-22 12:49 ` [patch V4 11/12] x86/futex: " Thomas Gleixner
2025-10-22 12:49 ` [patch V4 12/12] select: " Thomas Gleixner
2025-10-22 13:28 ` [patch V4 00/12] uaccess: Provide and use scopes for " Peter Zijlstra
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