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Message-ID: <b6b3d965-c1d4-4c18-8db4-2e7c19f10a15@proton.me>
Date: Wed, 14 Aug 2024 16:21:38 +0000
From: Benno Lossin <benno.lossin@...ton.me>
To: Danilo Krummrich <dakr@...nel.org>, ojeda@...nel.org, alex.gaynor@...il.com, wedsonaf@...il.com, boqun.feng@...il.com, gary@...yguo.net, bjorn3_gh@...tonmail.com, a.hindborg@...sung.com, aliceryhl@...gle.com, akpm@...ux-foundation.org
Cc: daniel.almeida@...labora.com, faith.ekstrand@...labora.com, boris.brezillon@...labora.com, lina@...hilina.net, mcanal@...lia.com, zhiw@...dia.com, cjia@...dia.com, jhubbard@...dia.com, airlied@...hat.com, ajanulgu@...hat.com, lyude@...hat.com, linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v5 04/26] rust: alloc: implement `Allocator` for `Kmalloc`
On 12.08.24 20:22, Danilo Krummrich wrote:
> + /// # Safety
> + ///
> + /// This method has the same safety requirements as `Allocator::realloc`.
Please make this a link.
> + unsafe fn call(
> + &self,
> + ptr: Option<NonNull<u8>>,
> + layout: Layout,
> + flags: Flags,
> + ) -> Result<NonNull<[u8]>, AllocError> {
> + let size = aligned_size(layout);
> + let ptr = match ptr {
> + Some(ptr) => ptr.as_ptr(),
> + None => ptr::null(),
> + };
> +
> + // SAFETY: `ptr` is either NULL or valid by the safety requirements of this function.
> + let raw_ptr = unsafe {
> + // If `size == 0` and `ptr != NULL` the memory behind the pointer is freed.
> + self.0(ptr.cast(), size, flags.0).cast()
> + };
> +
> + let ptr = if size == 0 {
Why do you do this check *after* calling `self.0`?
---
Cheers,
Benno
> + NonNull::dangling()
> + } else {
> + NonNull::new(raw_ptr).ok_or(AllocError)?
> + };
> +
> + Ok(NonNull::slice_from_raw_parts(ptr, size))
> + }
> +}
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