[patch V5 10/12] futex: Convert to get/put_user_inline()

[Mathieu Desnoyers]

On 2025-10-28 11:56, Thomas Gleixner wrote:
> On Tue, Oct 28 2025 at 10:24, Mathieu Desnoyers wrote:
>> On 2025-10-27 04:44, Thomas Gleixner wrote:
>>> From: Thomas Gleixner <tglx at 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.

AFAIU there was justification from Linus in
commit 43a43faf5376 ("futex: improve user space accesses").

Perhaps it's good enough to refer to that prior justification
in the commit message.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com