[PATCH v2] rust: Test page_align usize::MAX boundary edges

[PATCH v2] rust: Test page_align usize::MAX boundary edges

[bshephar]

From: Brendan Shephard <bshephar@bne-home.net>

Update `page_align` doc tests to test `usize::MAX` boundaries
rather than arbitrary middle of `PAGE_SIZE`.

Signed-off-by: Brendan Shephard <bshephar@bne-home.net>
---
This change is a follow-up to:
https://lore.kernel.org/rust-for-linux/CANiq72mLPvB_6Ow3bW5-V4-km=RyA59chQ1g1x9qUt2P-zZweg@mail.gmail.com/

Changes in v2:
- Change test comment back to explicitly mentioning overflow condition
- Updated commit message to remove follow-up comment.

 rust/kernel/page.rs | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/rust/kernel/page.rs b/rust/kernel/page.rs
index adecb200c654..c8dafdd843d7 100644
--- a/rust/kernel/page.rs
+++ b/rust/kernel/page.rs
@@ -45,9 +45,10 @@
 /// assert_eq!(page_align(0x1), Some(PAGE_SIZE));
 /// assert_eq!(page_align(PAGE_SIZE + 1), Some(2 * PAGE_SIZE));
 ///
-/// // Requested address causes overflow (returns `None`).
-/// let overflow_addr = usize::MAX - (PAGE_SIZE / 2);
-/// assert_eq!(page_align(overflow_addr), None);
+/// // Requested address causes overflow.
+/// assert_eq!(page_align(usize::MAX - PAGE_SIZE + 1), Some(usize::MAX - PAGE_SIZE + 1));
+/// assert_eq!(page_align(usize::MAX - PAGE_SIZE + 2), None);
+/// assert_eq!(page_align(usize::MAX), None);
 /// ```
 #[inline(always)]
 pub const fn page_align(addr: usize) -> Option<usize> {

base-commit: 7acc70476f14661149774ab88d3fe23d83ba4249
-- 
2.52.0