linux-kernel - [RFC PATCH v1 31/57] edac: Remove PAGE_SIZE compile-time constant assumption

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Message-ID: <20241014105912.3207374-31-ryan.roberts@arm.com>
Date: Mon, 14 Oct 2024 11:58:38 +0100
From: Ryan Roberts <ryan.roberts@....com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Anshuman Khandual <anshuman.khandual@....com>,
	Ard Biesheuvel <ardb@...nel.org>,
	Catalin Marinas <catalin.marinas@....com>,
	David Hildenbrand <david@...hat.com>,
	Greg Marsden <greg.marsden@...cle.com>,
	Ivan Ivanov <ivan.ivanov@...e.com>,
	Kalesh Singh <kaleshsingh@...gle.com>,
	Marc Zyngier <maz@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Matthias Brugger <mbrugger@...e.com>,
	Miroslav Benes <mbenes@...e.cz>,
	Will Deacon <will@...nel.org>
Cc: Ryan Roberts <ryan.roberts@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [RFC PATCH v1 31/57] edac: Remove PAGE_SIZE compile-time constant assumption

To prepare for supporting boot-time page size selection, refactor code
to remove assumptions about PAGE_SIZE being compile-time constant. Code
intended to be equivalent when compile-time page size is active.

Convert PAGES_TO_MiB() and MiB_TO_PAGES() to use the ternary operator so
that they continue to work with boot-time page size; Boot-time page size
can't be used with CPP because it's value is not known at compile time.
For compile-time page size builds, the compiler will dead code strip for
the same result.

Signed-off-by: Ryan Roberts <ryan.roberts@....com>
---

***NOTE***
Any confused maintainers may want to read the cover note here for context:
https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@arm.com/

 drivers/edac/edac_mc.h | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/edac/edac_mc.h b/drivers/edac/edac_mc.h
index 881b00eadf7a5..22132ee86e953 100644
--- a/drivers/edac/edac_mc.h
+++ b/drivers/edac/edac_mc.h
@@ -37,13 +37,12 @@
 #include <linux/workqueue.h>
 #include <linux/edac.h>
 
-#if PAGE_SHIFT < 20
-#define PAGES_TO_MiB(pages)	((pages) >> (20 - PAGE_SHIFT))
-#define MiB_TO_PAGES(mb)	((mb) << (20 - PAGE_SHIFT))
-#else				/* PAGE_SHIFT > 20 */
-#define PAGES_TO_MiB(pages)	((pages) << (PAGE_SHIFT - 20))
-#define MiB_TO_PAGES(mb)	((mb) >> (PAGE_SHIFT - 20))
-#endif
+#define PAGES_TO_MiB(pages)	(PAGE_SHIFT < 20 ?			\
+					((pages) >> (20 - PAGE_SHIFT)) :\
+					((pages) << (PAGE_SHIFT - 20)))
+#define MiB_TO_PAGES(mb)	(PAGE_SHIFT < 20 ?			\
+					((mb) << (20 - PAGE_SHIFT)) :	\
+					((mb) >> (PAGE_SHIFT - 20)))
 
 #define edac_printk(level, prefix, fmt, arg...) \
 	printk(level "EDAC " prefix ": " fmt, ##arg)
-- 
2.43.0