* [PATCH v2 1/2] rust: debugfs: migrate debugfs traits requirements to zerocopy
2026-07-28 17:31 [PATCH v2 0/2] rust: debugfs: migrate debugfs traits requirements to zerocopy Josef Ippisch via B4 Relay
@ 2026-07-28 17:31 ` Josef Ippisch via B4 Relay
2026-07-28 17:31 ` [PATCH v2 2/2] rust: debugfs: remove unsafe blocks from traits impl for Vec Josef Ippisch via B4 Relay
2026-07-31 9:09 ` [PATCH v2 0/2] rust: debugfs: migrate debugfs traits requirements to zerocopy Greg Kroah-Hartman
2 siblings, 0 replies; 4+ messages in thread
From: Josef Ippisch via B4 Relay @ 2026-07-28 17:31 UTC (permalink / raw)
To: Greg Kroah-Hartman, Rafael J. Wysocki, Danilo Krummrich,
Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
Andreas Hindborg, Alice Ryhl, Trevor Gross, Daniel Almeida,
Tamir Duberstein, Alexandre Courbot, Onur Özkan
Cc: driver-core, rust-for-linux, linux-kernel, Joshua Liebow-Feeser,
Miguel Ojeda, Josef Ippisch
From: Josef Ippisch <josef.ippisch.dev@mailbox.org>
Migrate `BinaryWriter` and `BinaryReaderMut`'s default implementation's
requirements on T from `kernel::transmute` traits to `zerocopy` traits.
The additional `zerocopy::Immutable` requirement on `BinaryWriter` does not
further restrict the types in practice but is rather a more explicit
requirement (that the type does not have interior mutability) and is
required by zerocopy for the `as_bytes()` function.
Suggested-by: Joshua Liebow-Feeser <joshlf@google.com>
Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/975
Link: https://github.com/Rust-for-Linux/linux/issues/1241
Signed-off-by: Josef Ippisch <josef.ippisch.dev@mailbox.org>
---
rust/kernel/debugfs/traits.rs | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)
diff --git a/rust/kernel/debugfs/traits.rs b/rust/kernel/debugfs/traits.rs
index 8c39524b6a99..b794f7dd7e14 100644
--- a/rust/kernel/debugfs/traits.rs
+++ b/rust/kernel/debugfs/traits.rs
@@ -18,10 +18,6 @@
Arc,
Mutex, //
},
- transmute::{
- AsBytes,
- FromBytes, //
- },
uaccess::{
UserSliceReader,
UserSliceWriter, //
@@ -36,6 +32,8 @@
str::FromStr,
};
+use zerocopy::Immutable;
+
/// A trait for types that can be written into a string.
///
/// This works very similarly to `Debug`, and is automatically implemented if `Debug` is
@@ -76,8 +74,8 @@ fn write_to_slice(
) -> Result<usize>;
}
-// Base implementation for any `T: AsBytes`.
-impl<T: AsBytes> BinaryWriter for T {
+// Base implementation for any `T: Immutable + IntoBytes`.
+impl<T: Immutable + IntoBytes> BinaryWriter for T {
fn write_to_slice(
&self,
writer: &mut UserSliceWriter,
@@ -147,7 +145,7 @@ fn write_to_slice(
// Delegate for `Vec<T, A>`.
impl<T, A> BinaryWriter for Vec<T, A>
where
- T: AsBytes,
+ T: Immutable + IntoBytes,
A: Allocator,
{
fn write_to_slice(
@@ -157,7 +155,7 @@ fn write_to_slice(
) -> Result<usize> {
let slice = self.as_slice();
- // SAFETY: `T: AsBytes` allows us to treat `&[T]` as `&[u8]`.
+ // 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))
};
@@ -230,14 +228,14 @@ fn read_from_slice_mut(
) -> Result<usize>;
}
-// Base implementation for any `T: AsBytes + FromBytes`.
-impl<T: AsBytes + FromBytes> BinaryReaderMut for T {
+// Base implementation for any `T: FromBytes + IntoBytes`.
+impl<T: FromBytes + IntoBytes> BinaryReaderMut for T {
fn read_from_slice_mut(
&mut self,
reader: &mut UserSliceReader,
offset: &mut file::Offset,
) -> Result<usize> {
- reader.read_slice_file(self.as_bytes_mut(), offset)
+ reader.read_slice_file(self.as_mut_bytes(), offset)
}
}
@@ -255,7 +253,7 @@ fn read_from_slice_mut(
// Delegate for `Vec<T, A>`: Support a `Vec<T, A>` with an outer lock.
impl<T, A> BinaryReaderMut for Vec<T, A>
where
- T: AsBytes + FromBytes,
+ T: FromBytes + IntoBytes,
A: Allocator,
{
fn read_from_slice_mut(
@@ -265,7 +263,7 @@ fn read_from_slice_mut(
) -> Result<usize> {
let slice = self.as_mut_slice();
- // SAFETY: `T: AsBytes + FromBytes` allows us to treat `&mut [T]` as `&mut [u8]`.
+ // 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(),
--
2.53.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v2 2/2] rust: debugfs: remove unsafe blocks from traits impl for Vec
2026-07-28 17:31 [PATCH v2 0/2] rust: debugfs: migrate debugfs traits requirements to zerocopy Josef Ippisch via B4 Relay
2026-07-28 17:31 ` [PATCH v2 1/2] " Josef Ippisch via B4 Relay
@ 2026-07-28 17:31 ` Josef Ippisch via B4 Relay
2026-07-31 9:09 ` [PATCH v2 0/2] rust: debugfs: migrate debugfs traits requirements to zerocopy Greg Kroah-Hartman
2 siblings, 0 replies; 4+ messages in thread
From: Josef Ippisch via B4 Relay @ 2026-07-28 17:31 UTC (permalink / raw)
To: Greg Kroah-Hartman, Rafael J. Wysocki, Danilo Krummrich,
Boqun Feng, Gary Guo, Björn Roy Baron, Benno Lossin,
Andreas Hindborg, Alice Ryhl, Trevor Gross, Daniel Almeida,
Tamir Duberstein, Alexandre Courbot, Onur Özkan
Cc: driver-core, rust-for-linux, linux-kernel, Joshua Liebow-Feeser,
Miguel Ojeda, Josef Ippisch
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
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH v2 0/2] rust: debugfs: migrate debugfs traits requirements to zerocopy
2026-07-28 17:31 [PATCH v2 0/2] rust: debugfs: migrate debugfs traits requirements to zerocopy Josef Ippisch via B4 Relay
2026-07-28 17:31 ` [PATCH v2 1/2] " Josef Ippisch via B4 Relay
2026-07-28 17:31 ` [PATCH v2 2/2] rust: debugfs: remove unsafe blocks from traits impl for Vec Josef Ippisch via B4 Relay
@ 2026-07-31 9:09 ` Greg Kroah-Hartman
2 siblings, 0 replies; 4+ messages in thread
From: Greg Kroah-Hartman @ 2026-07-31 9:09 UTC (permalink / raw)
To: josef.ippisch.dev
Cc: Rafael J. Wysocki, Danilo Krummrich, Boqun Feng, Gary Guo,
Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
Trevor Gross, Daniel Almeida, Tamir Duberstein, Alexandre Courbot,
Onur Özkan, driver-core, rust-for-linux, linux-kernel,
Joshua Liebow-Feeser, Miguel Ojeda
On Tue, Jul 28, 2026 at 07:31:18PM +0200, Josef Ippisch via B4 Relay wrote:
> Migrate `BinaryWriter` and `BinaryReaderMut`'s default implementation's
> requirements on T from `kernel::transmute` traits to `zerocopy` traits.
>
> This is part of a bigger migration from rust/kernel/transmute.rs to the
> zerocopy crate, see also [1] and [2]
>
> [1] https://github.com/Rust-for-Linux/linux/issues/975
> [2] https://github.com/Rust-for-Linux/linux/issues/1241
>
> The crate zerocopy was introduced with
>
> c37398010a05 rust: zerocopy: import crate
>
> This introduced among other things the `FromBytes` and `IntoBytes` traits
> that, when derived, do better checks on the actual requirements of the
> types they are implemented on than the existing
> `kernel::transmute::FromBytes` and `kernel::transmute::AsBytes` traits,
> respectively.
>
> This is my first kernel patch so please let me know if I do anything wrong
> process wise or regarding some other aspect!
>
> I noticed that we could probably get rid of the `BinaryWriter` and
> `BinaryReaderMut` implementations for `Vec` altogether if we implemented
> `FromBytes`, `Immutable` and `IntoBytes` for `Vec`. These are already
> implemented for [T] after all. What do you think?
>
> Suggested-by: Joshua Liebow-Feeser <joshlf@google.com>
> Suggested-by: Miguel Ojeda <ojeda@kernel.org>
> Link: https://github.com/Rust-for-Linux/linux/issues/975
> Link: https://github.com/Rust-for-Linux/linux/issues/1241
> Signed-off-by: Josef Ippisch <josef.ippisch.dev@mailbox.org>
> ---
> Changes in v2:
> - Addresses Sashiko AI review's comment about also migrating
> `BinaryReaderMut` to zerocopy to not bifurcate the API requirements of
> debugfs/traits.rs.
> - Do not `use zerocopy::{FromBytes, IntoBytes}` as they are part of
> `use kernel::prelude::*`.
> - For some reason sending v2 via SMTP server did not reach the mailing
> list. I apologize if some of you receive this twice now. I did not
> mark this RESEND because of the email never reaching the mailing list.
> - Link to v1: https://patch.msgid.link/20260719-migrate-binarywriter-to-zerocopy-intobytes-v1-0-27ed30512e75@mailbox.org
>
> ---
> Josef Ippisch (2):
> rust: debugfs: migrate debugfs traits requirements to zerocopy
> rust: debugfs: remove unsafe blocks from traits impl for Vec
>
> rust/kernel/debugfs/traits.rs | 41 +++++++++++------------------------------
> 1 file changed, 11 insertions(+), 30 deletions(-)
Always nice to delete code!
now queued up, thanks.
greg k-h
^ permalink raw reply [flat|nested] 4+ messages in thread