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From: "Thomas Weißschuh" <linux@weissschuh.net>
To: "David S. Miller" <davem@davemloft.net>,
	 Andreas Larsson <andreas@gaisler.com>,
	 Ankur Arora <ankur.a.arora@oracle.com>,
	 Andrew Morton <akpm@linux-foundation.org>,
	 "David Hildenbrand (Red Hat)" <david@kernel.org>
Cc: sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Thomas Weißschuh" <linux@weissschuh.net>
Subject: [PATCH v2] sparc: Avoid -Wunused-but-set-parameter in clear_user_page()
Date: Mon, 25 May 2026 10:36:21 +0200	[thread overview]
Message-ID: <20260525-sparc-clear_user_page-v2-1-e7a47fbcf439@weissschuh.net> (raw)

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().

Fixes: 62a9f5a85b98 ("mm: introduce clear_pages() and clear_user_pages()")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
Changes in v2:
- Put parens around vaddr.
- Link to v1: https://patch.msgid.link/20260524-sparc-clear_user_page-v1-1-baa5b90e5d0d@weissschuh.net
---
 arch/sparc/include/asm/page_32.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/sparc/include/asm/page_32.h b/arch/sparc/include/asm/page_32.h
index c1bccbedf567..9f0b54f70908 100644
--- a/arch/sparc/include/asm/page_32.h
+++ b/arch/sparc/include/asm/page_32.h
@@ -20,10 +20,12 @@
 #define clear_user_page(addr, vaddr, page)	\
 	do { 	clear_page(addr);		\
 		sparc_flush_page_to_ram(page);	\
+		(void)(vaddr);			\
 	} while (0)
 #define copy_user_page(to, from, vaddr, page)	\
 	do {	copy_page(to, from);		\
 		sparc_flush_page_to_ram(page);	\
+		(void)(vaddr);			\
 	} while (0)
 
 /* The following structure is used to hold the physical

---
base-commit: d87895ce6e45997825cfe1b3565a1843e8ac8011
change-id: 20260523-sparc-clear_user_page-7448669a2476

Best regards,
--  
Thomas Weißschuh <linux@weissschuh.net>


             reply	other threads:[~2026-05-25  8:36 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-25  8:36 Thomas Weißschuh [this message]
2026-05-25 17:44 ` Andrew Morton
2026-05-25 19:48   ` Thomas Weißschuh
2026-05-25 20:39     ` Andrew Morton
2026-06-12  9:15 ` Andreas Larsson

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