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

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Message-ID: <732f9f29-f794-4491-b942-45ad01b01db5@icloud.com>
Date: Sat, 22 Feb 2025 18:38:06 +0800
From: Zijun Hu <zijun_hu@...oud.com>
To: Arnd Bergmann <arnd@...db.de>, Zijun Hu <quic_zijuhu@...cinc.com>,
 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>,
 Nicholas Piggin <npiggin@...il.com>, Peter Zijlstra <peterz@...radead.org>,
 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>, Johannes Berg <johannes@...solutions.net>,
 Jamal Hadi Salim <jhs@...atatu.com>, Cong Wang <xiyou.wangcong@...il.com>,
 Jiri Pirko <jiri@...nulli.us>, Jason Gunthorpe <jgg@...pe.ca>,
 Leon Romanovsky <leon@...nel.org>, Linus Walleij <linus.walleij@...aro.org>,
 Bartosz Golaszewski <brgl@...ev.pl>, Lee Jones <lee@...nel.org>,
 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>
Cc: Linux-Arch <linux-arch@...r.kernel.org>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
 Netdev <netdev@...r.kernel.org>, linux-wireless@...r.kernel.org,
 linux-rdma@...r.kernel.org,
 "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
 linux-pm@...r.kernel.org, iommu@...ts.linux.dev,
 linux-mtd@...ts.infradead.org
Subject: Re: [PATCH *-next 00/18] Remove weird and needless 'return' for void
 APIs

On 2025/2/21 23:40, Arnd Bergmann wrote:
>> This patch series is to remove weird and needless 'return' for
>> void APIs under include/ with the following pattern:
>>
>> api_header.h:
>>
>> void api_func_a(...);
>>
>> static inline void api_func_b(...)
>> {
>> 	return api_func_a(...);
>> }
>>
>> Remove the needless 'return' in api_func_b().
>>
>> Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.com>
> I have no objection to the changes, but I think you should
> describe the motivation for them beyond them being 'weird'.
> 

yes. 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.

do we need to treat below return statement as bad code style ?

void api_func_a(...);
void api_func_b(...) {
...
	return api_func_a(...); // return void function in void func
...
}

> Do these 'return' statements get in the way of some other
> work you are doing? Is there a compiler warning you want
> to enable to ensure they don't come back? Is this all of
> the instances in the kernel or just the ones you found by
> inspection?

actually, i find this weird return usage by reading code by accident
in driver core firstly:
https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git/commit/?h=driver-core-testing&id=a44073c28bc6d4118891d61e31c9fa9dc4333dc0

then i check folder include/ and work out this patch series.

not sure if there are still such instances in current kernel tree.