All of lore.kernel.org
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	LKML <linux-kernel@vger.kernel.org>
Cc: "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,
	"Linus Torvalds" <torvalds@linux-foundation.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,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"David Laight" <david.laight.linux@gmail.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 V5 10/12] futex: Convert to get/put_user_inline()
Date: Tue, 28 Oct 2025 16:56:03 +0100	[thread overview]
Message-ID: <87frb3uijw.ffs@tglx> (raw)
In-Reply-To: <0c979fe0-ee55-48be-bd0f-9bff71b88a1d@efficios.com>

On Tue, Oct 28 2025 at 10:24, Mathieu Desnoyers wrote:
> On 2025-10-27 04:44, Thomas Gleixner wrote:
>> From: Thomas Gleixner <tglx@linutronix.de>
>> 
>> Replace the open coded implementation with the new get/put_user_inline()
>> helpers. This might be replaced by a regular get/put_user(), but that needs
>> a proper performance evaluation.
>
> I understand that this is aiming to keep the same underlying code,
> but I find it surprising that the first user of the "inline" get/put
> user puts the burden of the proof on moving this to regular
> get/put_user() rather than on using the inlined version.
>
> The comment above the inline API clearly states that performance
> numbers are needed to justify the use of inline, not the opposite.
>
> I am concerned that this creates a precedent that may be used by future
> users of the inline API to use it without performance numbers
> justification.

There was not justification for the open coded inline either and
converting it to get/put must be a completely seperate change.


WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx@linutronix.de>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	LKML <linux-kernel@vger.kernel.org>
Cc: "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,
	"Linus Torvalds" <torvalds@linux-foundation.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,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"David Laight" <david.laight.linux@gmail.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 V5 10/12] futex: Convert to get/put_user_inline()
Date: Tue, 28 Oct 2025 16:56:03 +0100	[thread overview]
Message-ID: <87frb3uijw.ffs@tglx> (raw)
In-Reply-To: <0c979fe0-ee55-48be-bd0f-9bff71b88a1d@efficios.com>

On Tue, Oct 28 2025 at 10:24, Mathieu Desnoyers wrote:
> On 2025-10-27 04:44, Thomas Gleixner wrote:
>> From: Thomas Gleixner <tglx@linutronix.de>
>> 
>> Replace the open coded implementation with the new get/put_user_inline()
>> helpers. This might be replaced by a regular get/put_user(), but that needs
>> a proper performance evaluation.
>
> I understand that this is aiming to keep the same underlying code,
> but I find it surprising that the first user of the "inline" get/put
> user puts the burden of the proof on moving this to regular
> get/put_user() rather than on using the inlined version.
>
> The comment above the inline API clearly states that performance
> numbers are needed to justify the use of inline, not the opposite.
>
> I am concerned that this creates a precedent that may be used by future
> users of the inline API to use it without performance numbers
> justification.

There was not justification for the open coded inline either and
converting it to get/put must be a completely seperate change.

_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv

  reply	other threads:[~2025-10-28 15:56 UTC|newest]

Thread overview: 113+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-10-27  8:43 [patch V5 00/12] uaccess: Provide and use scopes for user access Thomas Gleixner
2025-10-27  8:43 ` Thomas Gleixner
2025-10-27  8:43 ` [patch V5 01/12] ARM: uaccess: Implement missing __get_user_asm_dword() Thomas Gleixner
2025-10-27  8:43   ` Thomas Gleixner
2025-10-28 13:35   ` Mathieu Desnoyers
2025-10-28 13:35     ` Mathieu Desnoyers
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:48   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:43 ` [patch V5 02/12] uaccess: Provide ASM GOTO safe wrappers for unsafe_*_user() Thomas Gleixner
2025-10-27  8:43   ` Thomas Gleixner
2025-10-27 12:12   ` Andrew Cooper
2025-10-27 12:12     ` Andrew Cooper
2025-10-28 13:44   ` Mathieu Desnoyers
2025-10-28 13:44     ` Mathieu Desnoyers
2025-10-28 14:04   ` Yann Ylavic
2025-10-28 14:04     ` Yann Ylavic
2025-10-28 15:53     ` Thomas Gleixner
2025-10-28 15:53       ` Thomas Gleixner
2025-10-29  9:40       ` [patch V6 " Thomas Gleixner
2025-10-29  9:40         ` Thomas Gleixner
2025-10-29 10:24         ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:48         ` tip-bot2 for Thomas Gleixner
2025-12-19  8:10         ` [patch V6 02/12] " patchwork-bot+linux-riscv
2025-12-19  8:10           ` patchwork-bot+linux-riscv
2025-11-04  6:11   ` [patch V5 " Christophe Leroy
2025-11-04  6:11     ` Christophe Leroy
2025-10-27  8:43 ` [patch V5 03/12] x86/uaccess: Use unsafe wrappers for ASM GOTO Thomas Gleixner
2025-10-27  8:43   ` Thomas Gleixner
2025-10-28 13:50   ` Mathieu Desnoyers
2025-10-28 13:50     ` Mathieu Desnoyers
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:48   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:43 ` [patch V5 04/12] powerpc/uaccess: " Thomas Gleixner
2025-10-27  8:43   ` Thomas Gleixner
2025-10-28 13:51   ` Mathieu Desnoyers
2025-10-28 13:51     ` Mathieu Desnoyers
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:48   ` tip-bot2 for Thomas Gleixner
2025-11-04  6:15   ` [patch V5 04/12] " Christophe Leroy
2025-11-04  6:15     ` Christophe Leroy
2025-10-27  8:43 ` [patch V5 05/12] riscv/uaccess: " Thomas Gleixner
2025-10-27  8:43   ` Thomas Gleixner
2025-10-28 13:52   ` Mathieu Desnoyers
2025-10-28 13:52     ` Mathieu Desnoyers
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:48   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:43 ` [patch V5 06/12] s390/uaccess: " Thomas Gleixner
2025-10-27  8:43   ` Thomas Gleixner
2025-10-28 13:54   ` Mathieu Desnoyers
2025-10-28 13:54     ` Mathieu Desnoyers
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:48   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:43 ` [patch V5 07/12] uaccess: Provide scoped user access regions Thomas Gleixner
2025-10-27  8:43   ` Thomas Gleixner
2025-10-28 14:11   ` Mathieu Desnoyers
2025-10-28 14:11     ` Mathieu Desnoyers
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:48   ` tip-bot2 for Thomas Gleixner
2025-11-04  6:20   ` [patch V5 07/12] " Christophe Leroy
2025-11-04  6:20     ` Christophe Leroy
2025-11-04  8:17   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-07 19:17   ` [patch V5 07/12] " David Laight
2025-11-07 19:17     ` David Laight
2025-10-27  8:43 ` [patch V5 08/12] uaccess: Provide put/get_user_inline() Thomas Gleixner
2025-10-27  8:43   ` Thomas Gleixner
2025-10-28 14:12   ` Mathieu Desnoyers
2025-10-28 14:12     ` Mathieu Desnoyers
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:48   ` tip-bot2 for Thomas Gleixner
2025-11-04  6:30   ` [patch V5 08/12] " Christophe Leroy
2025-11-04  6:30     ` Christophe Leroy
2025-11-04  8:17   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-10-27  8:43 ` [patch V5 09/12] [RFC] coccinelle: misc: Add scoped_masked_$MODE_access() checker script Thomas Gleixner
2025-10-27  8:43   ` Thomas Gleixner
2025-10-27  8:44 ` [patch V5 10/12] futex: Convert to get/put_user_inline() Thomas Gleixner
2025-10-27  8:44   ` Thomas Gleixner
2025-10-28 14:24   ` Mathieu Desnoyers
2025-10-28 14:24     ` Mathieu Desnoyers
2025-10-28 15:56     ` Thomas Gleixner [this message]
2025-10-28 15:56       ` Thomas Gleixner
2025-10-28 16:02       ` Mathieu Desnoyers
2025-10-28 16:02         ` Mathieu Desnoyers
2025-10-28 16:13       ` Linus Torvalds
2025-10-28 16:13         ` Linus Torvalds
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:48   ` tip-bot2 for Thomas Gleixner
2025-11-04  6:31   ` [patch V5 10/12] " Christophe Leroy
2025-11-04  6:31     ` Christophe Leroy
2025-11-04  8:17   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V5 11/12] x86/futex: Convert to scoped user access Thomas Gleixner
2025-10-27  8:44   ` Thomas Gleixner
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:48   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V5 12/12] select: " Thomas Gleixner
2025-10-27  8:44   ` Thomas Gleixner
2025-10-28 14:42   ` Mathieu Desnoyers
2025-10-28 14:42     ` Mathieu Desnoyers
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  6:32   ` [patch V5 12/12] " Christophe Leroy
2025-11-04  6:32     ` Christophe Leroy
2025-11-04  8:17   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-10-27 15:53 ` [patch V5 00/12] uaccess: Provide and use scopes for " Linus Torvalds
2025-10-27 15:53   ` Linus Torvalds
2025-10-29 10:23 ` Peter Zijlstra
2025-10-29 10:23   ` Peter Zijlstra
2025-11-03 14:46   ` Peter Zijlstra
2025-11-03 14:46     ` Peter Zijlstra
2025-11-04  6:35 ` Christophe Leroy
2025-11-04  6:35   ` Christophe Leroy
2025-12-19  8:10 ` patchwork-bot+linux-riscv
2025-12-19  8:10   ` patchwork-bot+linux-riscv

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87frb3uijw.ffs@tglx \
    --to=tglx@linutronix.de \
    --cc=Julia.Lawall@inria.fr \
    --cc=andrealmeid@igalia.com \
    --cc=andrew.cooper3@citrix.com \
    --cc=borntraeger@linux.ibm.com \
    --cc=brauner@kernel.org \
    --cc=christophe.leroy@csgroup.eu \
    --cc=dave@stgolabs.net \
    --cc=david.laight.linux@gmail.com \
    --cc=dvhart@infradead.org \
    --cc=hca@linux.ibm.com \
    --cc=jack@suse.cz \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=lkp@intel.com \
    --cc=maddy@linux.ibm.com \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=mpe@ellerman.id.au \
    --cc=nicolas.palix@imag.fr \
    --cc=npiggin@gmail.com \
    --cc=palmer@dabbelt.com \
    --cc=peterz@infradead.org \
    --cc=pjw@kernel.org \
    --cc=svens@linux.ibm.com \
    --cc=torvalds@linux-foundation.org \
    --cc=viro@zeniv.linux.org.uk \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.