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

[Thomas Zimmermann]

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@xxxxxxx>
> > ---
> > 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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