linux-kernel - Re: [PATCH *-next 00/18] Remove weird and needless 'return' for void APIs

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Message-ID: <a2cf1f09-83d7-402b-94c1-88feec10a513@icloud.com>
Date: Sat, 22 Feb 2025 18:51:17 +0800
From: Zijun Hu <zijun_hu@...oud.com>
To: Johannes Berg <johannes@...solutions.net>,
 Stephen Hemminger <stephen@...workplumber.org>,
 Zijun Hu <quic_zijuhu@...cinc.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Will Deacon <will@...nel.org>, "Aneesh Kumar K.V" <aneesh.kumar@...nel.org>,
 Andrew Morton <akpm@...ux-foundation.org>, Nick Piggin <npiggin@...il.com>,
 Peter Zijlstra <peterz@...radead.org>, Arnd Bergmann <arnd@...db.de>,
 Thomas Gleixner <tglx@...utronix.de>,
 Herbert Xu <herbert@...dor.apana.org.au>,
 "David S. Miller" <davem@...emloft.net>,
 "Rafael J. Wysocki" <rafael@...nel.org>, Danilo Krummrich <dakr@...nel.org>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
 Jamal Hadi Salim <jhs@...atatu.com>, Cong Wang <xiyou.wangcong@...il.com>,
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 Thomas Graf <tgraf@...g.ch>, Christoph Hellwig <hch@....de>,
 Marek Szyprowski <m.szyprowski@...sung.com>,
 Robin Murphy <robin.murphy@....com>,
 Miquel Raynal <miquel.raynal@...tlin.com>,
 Richard Weinberger <richard@....at>, Vignesh Raghavendra <vigneshr@...com>,
 linux-arch@...r.kernel.org, linux-mm@...ck.org,
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Subject: Re: [PATCH *-next 00/18] Remove weird and needless 'return' for void
 APIs

On 2025/2/22 03:36, Johannes Berg wrote:
> On Fri, 2025-02-21 at 11:00 -0800, Stephen Hemminger wrote:
>> Is this something that could be done with a coccinelle script?
>>
> Almost enough to do this:
> 
> @@
> identifier fn;
> expression E;
> @@
> void fn(...)
> {
> ...
> -return
> E;
> }
> 
> 
> It takes a long time to run though, and does some wrong things as well:
> if the return is in the middle of the function, it still matches and
> removes it erroneously.

if return is in the middle, we may need to convert the return statement
in to two statement as [PATCH 18/18] does:
https://lore.kernel.org/all/20250221-rmv_return-v1-18-cc8dff275827@quicinc.com/

namely, Convert  "return func(...);" to "func(...); return;"

C spec such as C17 have this description about return
statement:
6.8.6.4:
A return statement with an expression shall not appear in a function
whose return type is void. A return statement without an expression
shall only appear in a function whose return type is void.

so, do we need to treat "return void function in void function" as
bad code style and make coccinelle script check this bad usage?