linux-kernel - Re: [PATCH v2] of: Fix of platform build on powerpc due to bad of disaply code

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Message-ID: <57e026bf-c412-0c47-8956-b565894948e0@suse.de>
Date:   Thu, 19 Jan 2023 14:11:13 +0100
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Christophe Leroy <christophe.leroy@...roup.eu>,
        Michal Suchanek <msuchanek@...e.de>,
        "Erhard F." <erhard_f@...lbox.org>,
        Rob Herring <robh+dt@...nel.org>
Cc:     "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE" 
        <devicetree@...r.kernel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Javier Martinez Canillas <javierm@...hat.com>,
        open list <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH v2] of: Fix of platform build on powerpc due to bad of
 disaply code

Hi

Am 19.01.23 um 11:24 schrieb Christophe Leroy:
> 
> 
> Le 19/01/2023 à 10:53, Michal Suchanek a écrit :
>> The commit 2d681d6a23a1 ("of: Make of framebuffer devices unique")
>> breaks build because of wrong argument to snprintf. That certainly
>> avoids the runtime error but is not the intended outcome.
>>
>> Also use standard device name format of-display.N for all created
>> devices.
>>
>> Fixes: 2d681d6a23a1 ("of: Make of framebuffer devices unique")
>> Signed-off-by: Michal Suchanek <msuchanek@...e.de>
>> ---
>> v2: Update the device name format
>> ---
>>    drivers/of/platform.c | 12 ++++++++----
>>    1 file changed, 8 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
>> index f2a5d679a324..8c1b1de22036 100644
>> --- a/drivers/of/platform.c
>> +++ b/drivers/of/platform.c
>> @@ -525,7 +525,9 @@ static int __init of_platform_default_populate_init(void)
>>    	if (IS_ENABLED(CONFIG_PPC)) {
>>    		struct device_node *boot_display = NULL;
>>    		struct platform_device *dev;
>> -		int display_number = 1;
>> +		int display_number = 0;
>> +		char buf[14];
> 
> Can you declare that in the for block where it is used instead ?
> 
>> +		char *of_display_format = "of-display.%d";
> 
> Should be const ?

That should be static const of_display_format[] = then

> 
>>    		int ret;
>>    
>>    		/* Check if we have a MacOS display without a node spec */
>> @@ -556,7 +558,10 @@ static int __init of_platform_default_populate_init(void)
>>    			if (!of_get_property(node, "linux,opened", NULL) ||
>>    			    !of_get_property(node, "linux,boot-display", NULL))
>>    				continue;
>> -			dev = of_platform_device_create(node, "of-display", NULL);
>> +			ret = snprintf(buf, sizeof(buf), of_display_format, display_number++);
>> +			if (ret >= sizeof(buf))
>> +				continue;
> 
> 
> Can you make buf big enough to avoid that ?
> 
> And by the way could it be called something else than 'buf' ?
> 
> See exemple here :
> https://elixir.bootlin.com/linux/v6.1/source/drivers/fsi/fsi-occ.c#L690
> 
> 
>> +			dev = of_platform_device_create(node, buf, NULL);
>>    			if (WARN_ON(!dev))
>>    				return -ENOMEM;
>>    			boot_display = node;
>> @@ -564,10 +569,9 @@ static int __init of_platform_default_populate_init(void)
>>    		}
>>    
>>    		for_each_node_by_type(node, "display") {
>> -			char *buf[14];
>>    			if (!of_get_property(node, "linux,opened", NULL) || node == boot_display)
>>    				continue;
>> -			ret = snprintf(buf, "of-display-%d", display_number++);
>> +			ret = snprintf(buf, sizeof(buf), of_display_format, display_number++);
>>    			if (ret >= sizeof(buf))
>>    				continue;
>>    			of_platform_device_create(node, buf, NULL);

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

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