[PATCH v2 2/2] rust: debugfs: remove unsafe blocks from traits impl for Vec

[Josef Ippisch via B4 Relay <devnull+josef.ippisch.dev.mailbox.org@kernel.org>]

From: Josef Ippisch <josef.ippisch.dev@mailbox.org>

The previous implementation used an `unsafe` block to manually cast Vec's
slice to a &[u8] using `core::slice::from_raw_parts`.  Instead, the
implementation can be implemented in safe rust using zerocopy's trait
functions `as_bytes()` and `as_mut_bytes()`, respectively, and making use
of deref coercion to implicitly cast Vec to &[T] as `FromBytes` and
`IntoBytes` automatically are implemented on [T] when they are implemented
on T.

Signed-off-by: Josef Ippisch <josef.ippisch.dev@mailbox.org>
---
 rust/kernel/debugfs/traits.rs | 21 ++-------------------
 1 file changed, 2 insertions(+), 19 deletions(-)

diff --git a/rust/kernel/debugfs/traits.rs b/rust/kernel/debugfs/traits.rs
index b794f7dd7e14..b295f8420abd 100644
--- a/rust/kernel/debugfs/traits.rs
+++ b/rust/kernel/debugfs/traits.rs
@@ -153,14 +153,7 @@ fn write_to_slice(
         writer: &mut UserSliceWriter,
         offset: &mut file::Offset,
     ) -> Result<usize> {
-        let slice = self.as_slice();
-
-        // SAFETY: `T: Immutable + IntoBytes` allows us to treat `&[T]` as `&[u8]`.
-        let buffer = unsafe {
-            core::slice::from_raw_parts(slice.as_ptr().cast(), core::mem::size_of_val(slice))
-        };
-
-        writer.write_slice_file(buffer, offset)
+        writer.write_slice_file(self.as_bytes(), offset)
     }
 }
 
@@ -261,17 +254,7 @@ fn read_from_slice_mut(
         reader: &mut UserSliceReader,
         offset: &mut file::Offset,
     ) -> Result<usize> {
-        let slice = self.as_mut_slice();
-
-        // SAFETY: `T: FromBytes + IntoBytes` allow us to treat `&mut [T]` as `&mut [u8]`.
-        let buffer = unsafe {
-            core::slice::from_raw_parts_mut(
-                slice.as_mut_ptr().cast(),
-                core::mem::size_of_val(slice),
-            )
-        };
-
-        reader.read_slice_file(buffer, offset)
+        reader.read_slice_file(self.as_mut_bytes(), offset)
     }
 }
 

-- 
2.53.0