linux-kernel - Re: [PATCH v2 2/2] tty: Fix race against tty_open() in tty_register_device

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Message-ID: <2a5432be-41b7-4adc-b68a-1f706036a59f@kernel.org>
Date: Tue, 3 Jun 2025 15:43:09 +0200
From: Jiri Slaby <jirislaby@...nel.org>
To: Max Staudt <max@...as.org>, Ilpo Järvinen
 <ilpo.jarvinen@...ux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Johan Hovold <johan@...nel.org>, linux-serial
 <linux-serial@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
 stable@...r.kernel.org
Subject: Re: [PATCH v2 2/2] tty: Fix race against tty_open() in
 tty_register_device_attr()

On 02. 06. 25, 15:40, Max Staudt wrote:
> On 6/2/25 19:31, Ilpo Järvinen wrote:
>>> +    mutex_lock(&tty_mutex);
>>
>> Use guard() so you don't need to change the returns and rollback path.
> 
> Thanks, I didn't know about this new kind of helper.
> 
> I'll leave it up to the TTY maintainers - if they don't express a 
> preference for guard(), 

I prefer guard(). Actually, I have a patchset to add a support for 
guard() for uart_lock and console_lock too and use it all over (incl. 
__free). They untangle the code on many places and get rid of much 
unneeded churn.

But in this very case, I see there is a label, I am not sure if it works 
right here. Try compiling with clang -- it will tell you. You likely 
won't cross the label with the guard().

thanks,
-- 
js
suse labs