linux-kernel - Re: [PATCH] hns3: work around stack size warning

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Message-Id: <a029763b-6a5c-48ed-b135-daf1d359ac24@app.fastmail.com>
Date: Wed, 11 Jun 2025 18:36:15 +0200
From: "Arnd Bergmann" <arnd@...db.de>
To: "Jijie Shao" <shaojijie@...wei.com>, "Arnd Bergmann" <arnd@...nel.org>,
 "Jian Shen" <shenjian15@...wei.com>, "Salil Mehta" <salil.mehta@...wei.com>,
 "Andrew Lunn" <andrew+netdev@...n.ch>,
 "David S . Miller" <davem@...emloft.net>,
 "Eric Dumazet" <edumazet@...gle.com>, "Jakub Kicinski" <kuba@...nel.org>,
 "Paolo Abeni" <pabeni@...hat.com>, "Nathan Chancellor" <nathan@...nel.org>
Cc: "Nick Desaulniers" <nick.desaulniers+lkml@...il.com>,
 "Bill Wendling" <morbo@...gle.com>, "Justin Stitt" <justinstitt@...gle.com>,
 "Hao Lan" <lanhao@...wei.com>, "Guangwei Zhang" <zhangwangwei6@...wei.com>,
 Netdev <netdev@...r.kernel.org>, linux-kernel@...r.kernel.org,
 llvm@...ts.linux.dev
Subject: Re: [PATCH] hns3: work around stack size warning

On Wed, Jun 11, 2025, at 04:10, Jijie Shao wrote:
> on 2025/6/10 17:21, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@...db.de>
>>>>
>> Annotate hns3_dbg_tx_spare_info() as noinline_for_stack to force the
>> behavior that gcc has, regardless of the compiler.
>>
>> Ideally all the functions in here would be changed to avoid on-stack
>> output buffers.
>
> Would you please help test whether the following changes have solved 
> your problem,
> And I'm not sure if this patch should be sent to net or net-next...

Your patch arrived with whitespace corruption here, so I could not
try it, but I'm sure it would help avoid the warning.

However, this is not what meant with my suggestion: you already
allocate a temporary buffer in hns3_dbg_open() and I would
expect it to be possible to read into that buffer directly
without a second temporary buffer (on stack or kmalloc).

The normal way of doing this would be to use the infrastructure
from seq_file and then seq_printf() and not have any extra buffers
on top of that.

      Arnd