Re: [PATCH v2 09/13] lib/fonts: Compare font data for equality with font_data_is_equal()

[Thomas Zimmermann]

Hi

Am 05.03.26 um 01:23 schrieb Nathan Chancellor:
[...]
> >   
> > +static bool font_data_is_internal(font_data_t *fd)
> > +{
> > +	return is_kernel_rodata((unsigned long)fd);
> > +}
> > +
[...]
> > This breaks the build when CONFIG_FONT_SUPPORT is a module.
> >
> >    $ cat allno.config
> >    CONFIG_MODULES=y
> >    CONFIG_DRM=m
> >    CONFIG_DRM_PANIC=y
> >
> >    $ make -skj"$(nproc)" ARCH=x86_64 CROSS_COMPILE=x86_64-linux- KCONFIG_ALLCONFIG=1 allnoconfig all
> >    ERROR: modpost: "__end_rodata" [lib/fonts/font.ko] undefined!
> >    make[4]: *** [scripts/Makefile.modpost:147: Module.symvers] Error 1
> >    ...
> >
> >    $ scripts/config -s FONT_SUPPORT
> >    m

Thanks for testing. The attached patch fixes the problem for me. Could 
you please test?

Best regards
Thomas

> > Cheers,
> > Nathan
> >
> >
> > +	if (font_data_size(lhs) != font_data_size(rhs))
> > +		return false;
> > +	if (FNTSUM(lhs) && FNTSUM(rhs) && FNTSUM(lhs) != FNTSUM(rhs))
> > +		return false;
> > +
> > +	return !memcmp(lhs, rhs, FNTSIZE(lhs));
> > +}
> > +EXPORT_SYMBOL_GPL(font_data_is_equal);
> > +
> >   /*
> >    * Font lookup
> >    */
> > --
> > 2.53.0

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)

From 8dc48d2e676d1437584794f4df3dd20d08878655 Mon Sep 17 00:00:00 2001
From: Thomas Zimmermann <tzimmermann@xxxxxxx>
Date: Thu, 5 Mar 2026 09:28:28 +0100
Subject: [PATCH] test for internal fonts by refcount

Internal font data is 'static const'. Hence test against the refcount
being zero.
---
 lib/fonts/fonts.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/lib/fonts/fonts.c b/lib/fonts/fonts.c
index 198aae869be2..b73d74b977ec 100644
--- a/lib/fonts/fonts.c
+++ b/lib/fonts/fonts.c
@@ -45,14 +45,11 @@ static struct font_data *to_font_data_struct(font_data_t *fd)
 
 static bool font_data_is_internal(font_data_t *fd)
 {
-	return is_kernel_rodata((unsigned long)fd);
+	return !REFCOUNT(fd); /* internal fonts have no reference counting */
 }
 
 static void font_data_free(font_data_t *fd)
 {
-	if (WARN_ON(font_data_is_internal(fd)))
-		return;
-
 	kfree(to_font_data_struct(fd));
 }
 
-- 
2.53.0