linux-kernel - Re: [PATCH] serial: core: Add support for dev

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Message-ID: <c0061557-1dc7-0442-b5e0-3e528d0bebb1@kernel.org>
Date:   Wed, 19 Jul 2023 07:36:33 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andriy.shevchenko@...el.com>,
        Dhruva Gole <d-gole@...com>,
        Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
        John Ogness <john.ogness@...utronix.de>,
        Johan Hovold <johan@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-omap@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] serial: core: Add support for dev_name:0.0 naming for
 kernel console

On 19. 07. 23, 7:32, Tony Lindgren wrote:
> * Jiri Slaby <jirislaby@...nel.org> [230719 05:29]:
>> On 19. 07. 23, 7:28, Tony Lindgren wrote:
>>> * Jiri Slaby <jirislaby@...nel.org> [230719 05:25]:
>>>> On 19. 07. 23, 7:15, Tony Lindgren wrote:
>>>>> +/*
>>>>> + * Add preferred console if configured on kernel command line with naming
>>>>> + * "console=dev_name:0.0".
>>>>> + */
>>>>> +static int serial_core_add_preferred_console(struct uart_driver *drv,
>>>>> +					     struct uart_port *port)
>>>>> +{
>>>>> +	char *port_match, *opt, *name;
>>>>> +	int len, ret = 0;
>>>>> +
>>>>> +	port_match = kasprintf(GFP_KERNEL, "console=%s:%i.%i",
>>>>> +			       dev_name(port->dev), port->ctrl_id,
>>>>> +			       port->port_id);
>>>>> +	if (!port_match)
>>>>> +		return -ENOMEM;
>>>>> +
>>>>> +	opt = strstr(saved_command_line, port_match);
>>>>> +	if (!opt)
>>>>> +		goto free_port_match;
>>>>> +
>>>>> +	len = strlen(port_match);
>>>>> +
>>>>> +	if (strlen(opt) > len + 1 && opt[len] == ',')
>>>>> +		opt += len + 1;
>>>>> +	else
>>>>> +		opt = NULL;
>>>>> +
>>>>> +	name = kstrdup(drv->dev_name, GFP_KERNEL);
>>>>
>>>> Why do you dup the name here?
>>>
>>> I was getting ignoring const warning, but maybe the right solution is
>>> to just use const char *name here.. Let me check.
>>
>> So fix add_preferred_console() instead ;).
> 
> Let's see what kind of trouble changing it to use const char *name
> might be.

I don't see any, the string is copied internally. So it should be 
straightforward. Actually all three parameters of 
__add_preferred_console() should be const, IMO. But that involves 
changing struct console_cmdline. But that should be straightforward too.


Aside from that, why do you parse saved_command_line on your own? 
Instead of using setup() or other commonly used mechanisms for command 
line handling?

thanks,
-- 
js
suse labs