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From:   John Ogness <john.ogness@linutronix.de>
To:     Petr Mladek <pmladek@suse.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Sergey Senozhatsky <senozhatsky@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Ilpo =?utf-8?Q?J=C3=A4rvi?= =?utf-8?Q?nen?= 
        <ilpo.jarvinen@linux.intel.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Tony Lindgren <tony@atomide.com>,
        Lukas Wunner <lukas@wunner.de>, linux-serial@vger.kernel.org
Subject: Re: [PATCH printk v3 23/40] serial_core: replace
 uart_console_enabled() with uart_console_registered()
In-Reply-To: <Y2z7lLEvQx7iLuuP@alley>
References: <20221107141638.3790965-1-john.ogness@linutronix.de>
 <20221107141638.3790965-24-john.ogness@linutronix.de>
 <CAMuHMdXuBh1PznFggpwSanBtHu9=ngJkVCRzdZVnjxWs2+cbxw@mail.gmail.com>
 <Y2z7lLEvQx7iLuuP@alley>
Date:   Thu, 10 Nov 2022 14:52:20 +0106
Message-ID: <87fseq6hxv.fsf@jogness.linutronix.de>
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On 2022-11-10, Petr Mladek <pmladek@suse.com> wrote:
>>> -static inline bool uart_console_enabled(struct uart_port *port)
>>> +/* Variant of uart_console_registered() when the console_list_lock is held. */
>>> +static inline bool uart_console_registered_locked(struct uart_port *port)
>>>  {
>>> -       return uart_console(port) && (port->cons->flags & CON_ENABLED);
>>> +       return uart_console(port) && console_is_registered_locked(port->cons);
>>> +}
>>> +
>>> +static inline bool uart_console_registered(struct uart_port *port)
>>> +{
>>> +       bool ret;
>>> +
>>> +       console_list_lock();
>>> +       ret = uart_console_registered_locked(port);
>>> +       console_list_unlock();
>>> +       return ret;
>> 
>> Perhaps
>> 
>>     return uart_console(port) && console_is_registered();
>> 
>> to avoid locking the list when the first condition is not true?
>
> I do not have strong opinion on this. It is true that the code
> duplication is trivial but it is a code duplication. Either
> way would work for me.

I will go with Geert's suggestion for v4. It is important that we reduce
lock contention for non-console ports.

> The reset of the code looks good. Feel free to use:
>
> Reviewed-by: Petr Mladek <pmladek@suse.com>

Thanks.

John