linux-kernel - Re: [PATCH v2 3/4] Provide the always inline version of some functions

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Message-Id: <a034a57e-d9f1-4c56-87f0-e9126246849d@app.fastmail.com>
Date: Sun, 09 Nov 2025 18:35:23 +0100
From: "Arnd Bergmann" <arnd@...db.de>
To: "Xie Yuanbin" <qq570070308@...il.com>,
 "Peter Zijlstra" <peterz@...radead.org>,
 "David Hildenbrand" <david@...hat.com>,
 "Thomas Gleixner" <tglx@...utronix.de>,
 "Segher Boessenkool" <segher@...nel.crashing.org>, riel@...riel.com,
 "Russell King" <linux@...linux.org.uk>,
 "Mathieu Desnoyers" <mathieu.desnoyers@...icios.com>,
 "Paul E. McKenney" <paulmck@...nel.org>, pjw@...nel.org,
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 "Uladzislau Rezki (Sony)" <urezki@...il.com>
Cc: x86@...nel.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
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 "Will Deacon" <will@...nel.org>
Subject: Re: [PATCH v2 3/4] Provide the always inline version of some functions

On Sun, Nov 9, 2025, at 18:04, Xie Yuanbin wrote:
> On Sun, 9 Nov 2025 12:31:52 +0100, Peter Zijlstra wrote:
> Adding the always-inline version of these functions can provide better
> guidance for compiler optimization, but it does indeed lead to more
> complex code.
> The best solution may be to prompt the compiler to always inline at a
> specific calling point through some keyword.
> I noticed that there are also people discussing this issue on stackerflow
> , but it seems that the current compiler does not have such a feature.
> Link: https://stackoverflow.com/questions/14571593

You can mark the caller as __attribute__((flatten)) to force all
functions to be inlined into that one if possible. I don't know
if that would be helpful or desired here though.

     Arnd