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charset="utf-8" To avoid hard-coding these values in drivers, define constants for them that drivers can reference. Acked-by: Danilo Krummrich Reviewed-by: Burak Emir Signed-off-by: Alice Ryhl --- rust/kernel/bitmap.rs | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/rust/kernel/bitmap.rs b/rust/kernel/bitmap.rs index aa8fc7bf06fc99865ae755d8694e4bec3dc8e7f0..15fa23b45054b9272415fcc000e3e3b52c74d7c1 100644 --- a/rust/kernel/bitmap.rs +++ b/rust/kernel/bitmap.rs @@ -149,14 +149,14 @@ macro_rules! bitmap_assert_return { /// /// # Invariants /// -/// * `nbits` is `<= i32::MAX` and never changes. +/// * `nbits` is `<= MAX_LEN`. /// * if `nbits <= bindings::BITS_PER_LONG`, then `repr` is a `usize`. /// * otherwise, `repr` holds a non-null pointer to an initialized /// array of `unsigned long` that is large enough to hold `nbits` bits. pub struct BitmapVec { /// Representation of bitmap. repr: BitmapRepr, - /// Length of this bitmap. Must be `<= i32::MAX`. + /// Length of this bitmap. Must be `<= MAX_LEN`. nbits: usize, } @@ -226,10 +226,16 @@ fn drop(&mut self) { } impl BitmapVec { + /// The maximum possible length of a `BitmapVec`. + pub const MAX_LEN: usize = i32::MAX as usize; + + /// The maximum length that avoids allocating. + pub const NO_ALLOC_MAX_LEN: usize = BITS_PER_LONG; + /// Constructs a new [`BitmapVec`]. /// /// Fails with [`AllocError`] when the [`BitmapVec`] could not be allocated. This - /// includes the case when `nbits` is greater than `i32::MAX`. + /// includes the case when `nbits` is greater than `MAX_LEN`. #[inline] pub fn new(nbits: usize, flags: Flags) -> Result { if nbits <= BITS_PER_LONG { @@ -238,11 +244,11 @@ pub fn new(nbits: usize, flags: Flags) -> Result { nbits, }); } - if nbits > i32::MAX.try_into().unwrap() { + if nbits > Self::MAX_LEN { return Err(AllocError); } let nbits_u32 = u32::try_from(nbits).unwrap(); - // SAFETY: `BITS_PER_LONG < nbits` and `nbits <= i32::MAX`. + // SAFETY: `BITS_PER_LONG < nbits` and `nbits <= MAX_LEN`. let ptr = unsafe { bindings::bitmap_zalloc(nbits_u32, flags.as_raw()) }; let ptr = NonNull::new(ptr).ok_or(AllocError)?; // INVARIANT: `ptr` returned by C `bitmap_zalloc` and `nbits` checked. -- 2.51.1.838.g19442a804e-goog