Re: [PATCH v2] rust: generalize userSliceReader to support any Vec

Boqun Feng
2025-01-08T19:07:32Z

On Tue, Jan 07, 2025 at 04:25:39PM -0300, Filipe Xavier wrote:
> The UserSliceReader::read_all function is currently restricted to use
> only Vec with the kmalloc allocator.
> However, there is no reason for this limitation.
> This patch generalizes the function to accept any Vec regardless of the
> allocator used.
> There's a use-case for a KVVec in Binder to avoid maximum
> sizes for a certain array.
>
> Link: https://github.com/Rust-for-Linux/linux/issues/1136
> Signed-off-by: Filipe Xavier <felipeaggger@gmail.com>

Reviewed-by: Boqun Feng <boqun.feng@gmail.com>

Regards,
Boqun

> ---
> Changes in v2:
> - Commit description: added use case on description and send to memorymanagment on copy.
> - Link to v1: https://lore.kernel.org/r/20241222-gen-userslice-readall-alloc-v1-1-c57b7d4972f0@gmail.com
> ---
> rust/kernel/uaccess.rs | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs
> index cc044924867b89f6116c7f9ec216d8cea2b3f8d7..719b0a48ff5550acc19f2e607c0a09f818145def 100644
> --- a/rust/kernel/uaccess.rs
> +++ b/rust/kernel/uaccess.rs
> @@ -5,7 +5,7 @@
> //! C header: [`include/linux/uaccess.h`](srctree/include/linux/uaccess.h)
>
> use crate::{
> - alloc::Flags,
> + alloc::{Allocator, Flags},
> bindings,
> error::Result,
> ffi::c_void,
> @@ -127,7 +127,7 @@ pub fn new(ptr: UserPtr, length: usize) -> Self {
> /// Reads the entirety of the user slice, appending it to the end of the provided buffer.
> ///
> /// Fails with [`EFAULT`] if the read happens on a bad address.
> - pub fn read_all(self, buf: &mut KVec<u8>, flags: Flags) -> Result {
> + pub fn read_all<A: Allocator>(self, buf: &mut Vec<u8, A>, flags: Flags) -> Result {
> self.reader().read_all(buf, flags)
> }
>
> @@ -281,7 +281,7 @@ pub fn read<T: FromBytes>(&mut self) -> Result<T> {
> /// Reads the entirety of the user slice, appending it to the end of the provided buffer.
> ///
> /// Fails with [`EFAULT`] if the read happens on a bad address.
> - pub fn read_all(mut self, buf: &mut KVec<u8>, flags: Flags) -> Result {
> + pub fn read_all<A: Allocator>(mut self, buf: &mut Vec<u8, A>, flags: Flags) -> Result {
> let len = self.length;
> buf.reserve(len, flags)?;
>
>
> ---
> base-commit: 0c5928deada15a8d075516e6e0d9ee19011bb000
> change-id: 20241222-gen-userslice-readall-alloc-8049c668e65e
>
> Best regards,
> --
> Filipe Xavier <felipeaggger@gmail.com>
>