Re: [PATCH v2] sparc: Avoid -Wunused-but-set-parameter in clear_user_page()

[Andrew Morton]

On Mon, 25 May 2026 10:36:21 +0200 Thomas Weißschuh <linux@xxxxxxxxxxxxxx> wrote:

> The loop in clear_user_pages() iterates over all pages and calls
> clear_user_page() for each of them. During the loop "vaddr" is modified.
> However on sparc clear_user() is a macro which does not use "vaddr".
> The compiler sees a variable which is modified but never used and emits
> a warning for that:
> 
> 	include/linux/highmem.h: In function 'clear_user_pages':
> 	include/linux/highmem.h:234:63: warning: parameter 'vaddr' set but not used [-Wunused-but-set-parameter=]
> 		static inline void clear_user_pages(void *addr, unsigned long vaddr,
> 
> Other architectures use an inline function for clear_user_page() which
> avoids the warning. This is not possible on sparc, as
> sparc_flush_page_to_ram() is not yet declared where clear_user_page() is
> defined. Including cacheflush_32.h will trigger recursive and lots of
> other issues.
> 
> So hide the warning with a cast to (void) instead.
> 
> While we are here, do the same for copy_user_page().

A pleasing solution to these sorts of problems is often "don't use
macros".  Other architectures use inlined C for these functions - will
that work for sparc?