[PATCH v2 02/21] rust: dma: expose the count and size of CoherentAllocation

Alexandre Courbot
2025-05-01T12:59:01Z

These properties are very useful to have and should be accessible.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
rust/kernel/dma.rs | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs
index 605e01e35715667f93297fd9ec49d8e7032e0910..18602d771054fceb80c29278b1945254312ed7c6 100644
--- a/rust/kernel/dma.rs
+++ b/rust/kernel/dma.rs
@@ -201,6 +201,20 @@ pub fn alloc_coherent(
CoherentAllocation::alloc_attrs(dev, count, gfp_flags, Attrs(0))
}

+ /// Returns the number of elements `T` in this allocation.
+ ///
+ /// Note that this is not the size of the allocation in bytes, which is provided by
+ /// [`Self::size`].
+ pub fn count(&self) -> usize {
+ self.count
+ }
+
+ /// Returns the size in bytes of this allocation.
+ pub fn size(&self) -> usize {
+ // This is guaranteed not to overflow as the same operation has been done in `alloc_attrs`.
+ self.count * core::mem::size_of::<T>()
+ }
+
/// Returns the base address to the allocated region in the CPU's virtual address space.
pub fn start_ptr(&self) -> *const T {
self.cpu_addr

--
2.49.0