linux-kernel - [RFC PATCH v1 33/57] random: Remove PAGE_SIZE compile-time constant assumption

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Message-ID: <20241014105912.3207374-33-ryan.roberts@arm.com>
Date: Mon, 14 Oct 2024 11:58:40 +0100
From: Ryan Roberts <ryan.roberts@....com>
To: "Jason A. Donenfeld" <Jason@...c4.com>,
	"Theodore Ts'o" <tytso@....edu>,
	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-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [RFC PATCH v1 33/57] random: 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.

Update BUILD_BUG_ON()s to test against page size limits.

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/char/random.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 87fe61295ea1f..49d6c4ef16df4 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -466,7 +466,7 @@ static ssize_t get_random_bytes_user(struct iov_iter *iter)
 		if (!iov_iter_count(iter) || copied != sizeof(block))
 			break;
 
-		BUILD_BUG_ON(PAGE_SIZE % sizeof(block) != 0);
+		BUILD_BUG_ON(PAGE_SIZE_MIN % sizeof(block) != 0);
 		if (ret % PAGE_SIZE == 0) {
 			if (signal_pending(current))
 				break;
@@ -1428,7 +1428,7 @@ static ssize_t write_pool_user(struct iov_iter *iter)
 		if (!iov_iter_count(iter) || copied != sizeof(block))
 			break;
 
-		BUILD_BUG_ON(PAGE_SIZE % sizeof(block) != 0);
+		BUILD_BUG_ON(PAGE_SIZE_MIN % sizeof(block) != 0);
 		if (ret % PAGE_SIZE == 0) {
 			if (signal_pending(current))
 				break;
-- 
2.43.0