linux-kernel - Re: [PATCH v2] serial: sifive: lock port in startup()/shutdown() callbacks

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Message-Id: <20250410142303.5978-1-ryotkkr98@gmail.com>
Date: Thu, 10 Apr 2025 23:23:03 +0900
From: Ryo Takakura <ryotkkr98@...il.com>
To: pmladek@...e.com
Cc: alex@...ti.fr,
	aou@...s.berkeley.edu,
	bigeasy@...utronix.de,
	conor.dooley@...rochip.com,
	gregkh@...uxfoundation.org,
	jirislaby@...nel.org,
	john.ogness@...utronix.de,
	linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-serial@...r.kernel.org,
	palmer@...belt.com,
	paul.walmsley@...ive.com,
	ryotkkr98@...il.com,
	samuel.holland@...ive.com,
	stable@...r.kernel.org,
	u.kleine-koenig@...libre.com
Subject: Re: [PATCH v2] serial: sifive: lock port in startup()/shutdown() callbacks

On Thu, 10 Apr 2025 13:29:43 +0200, Petr Mladek wrote:
>On Sat 2025-04-05 23:53:54, Ryo Takakura wrote:
>> startup()/shutdown() callbacks access SIFIVE_SERIAL_IE_OFFS.
>> The register is also accessed from write() callback.
>> 
>> If console were printing and startup()/shutdown() callback
>> gets called, its access to the register could be overwritten.
>> 
>> Add port->lock to startup()/shutdown() callbacks to make sure
>> their access to SIFIVE_SERIAL_IE_OFFS is synchronized against
>> write() callback.
>> 
>> Fixes: 45c054d0815b ("tty: serial: add driver for the SiFive UART")
>> Signed-off-by: Ryo Takakura <ryotkkr98@...il.com>
>> Cc: stable@...r.kernel.org
>
>I do not have the hardware around so I could not test it.
>But the change make sense. It fixes a real race.
>And the code looks reasonable:
>
>Reviewed-by: Petr Mladek <pmladek@...e.com>

Thanks for reviewing this one as well!
I'll send v3 with your Reviewed-by.

Sincerely,
Ryo Takakura

>Best Regards,
>Petr