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

[Thomas Zimmermann <tzimmermann@suse.de>]

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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)


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From 8dc48d2e676d1437584794f4df3dd20d08878655 Mon Sep 17 00:00:00 2001
From: Thomas Zimmermann <tzimmermann@suse.de>
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