Re: [PATCH v4 18/25] dyndbg: Upgrade class param storage to u64 for 64-bit classmaps

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Incomplete 64-bit conversion in `drm_debug_enabled_raw()` prevents checking categories >= 32 on 32-bit architectures.
--

commit 9ed1108f13f83f85b038d937d383fae3b647f69a
Author: Jim Cromie <jim.cromie@gmail.com>

dyndbg: Upgrade class param storage to u64 for 64-bit classmaps
    
This commit upgrades the dynamic debug class parameter storage to u64 to
support 64-bit classmaps without truncation on 32-bit architectures. It also
updates __drm_debug to use u64.

> diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
> index ab017b05e1751..21a0ced0b2f20 100644
> --- a/include/drm/drm_print.h
> +++ b/include/drm/drm_print.h
> @@ -39,7 +39,7 @@ struct drm_device;
>  struct seq_file;
>  
>  /* Do *not* use outside of drm_print.[ch]! */
> -extern unsigned long __drm_debug;
> +extern u64 __drm_debug;

[Severity: Low]
With __drm_debug upgraded to u64, does drm_debug_enabled_raw() also need
to be updated to use BIT_ULL() instead of BIT()?

Currently it evaluates using BIT():

static inline bool drm_debug_enabled_raw(enum drm_debug_category category)
{
	return unlikely(__drm_debug & BIT(category));
}

On 32-bit architectures, BIT() evaluates to a 32-bit unsigned long. While
this might not cause issues right now with the current number of debug
categories, it limits the 64-bit conversion and prevents checking categories
>= 32 since the bitwise operation would evaluate as 32-bit before the check
against __drm_debug.

Since the commit message notes "further changes to drm later", is this
already planned for a follow-up patch?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260602-dd-maint-2-v4-0-19a1445585a8@gmail.com?part=18