From: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
To: Alice Ryhl <aliceryhl@google.com>, rust-for-linux@vger.kernel.org
Cc: "Miguel Ojeda" <ojeda@kernel.org>,
"Wedson Almeida Filho" <wedsonaf@gmail.com>,
"Alex Gaynor" <alex.gaynor@gmail.com>,
"Boqun Feng" <boqun.feng@gmail.com>,
"Gary Guo" <gary@garyguo.net>,
"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
"Benno Lossin" <benno.lossin@proton.me>,
linux-kernel@vger.kernel.org, patches@lists.linux.dev
Subject: Re: [PATCH v1] rust: add improved version of `ForeignOwnable::borrow_mut`
Date: Thu, 13 Jul 2023 00:28:17 -0300 [thread overview]
Message-ID: <3c917bbd-7d53-23e2-d067-7ce8fce95307@gmail.com> (raw)
In-Reply-To: <20230710074642.683831-1-aliceryhl@google.com>
On 7/10/23 04:46, Alice Ryhl wrote:
> Previously, the `ForeignOwnable` trait had a method called `borrow_mut`
> that was intended to provide mutable access to the inner value. However,
> the method accidentally made it possible to change the address of the
> object being modified, which usually isn't what we want. (And when we
> want that, it can be done by calling `from_foreign` and `into_foreign`,
> like how the old `borrow_mut` was implemented.)
>
> In this patch, we introduce an alternate definition of `borrow_mut` that
> solves the previous problem. Conceptually, given a pointer type `P` that
> implements `ForeignOwnable`, the `borrow_mut` method gives you the same
> kind of access as an `&mut P` would, except that it does not let you
> change the pointer `P` itself.
>
> This is analogous to how the existing `borrow` method provides the same
> kind of access to the inner value as an `&P`.
>
> Note that for types like `Arc`, having an `&mut Arc<T>` only gives you
> immutable access to the inner `T`. This is because mutable references
> assume exclusive access, but there might be other handles to the same
> reference counted value, so the access isn't exclusive. The `Arc` type
> implements this by making `borrow_mut` return the same type as `borrow`.
>
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>
> ---
> [...]
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
next prev parent reply other threads:[~2023-07-13 3:28 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-10 7:46 [PATCH v1] rust: add improved version of `ForeignOwnable::borrow_mut` Alice Ryhl
2023-07-11 17:42 ` Boqun Feng
2023-07-14 10:28 ` Alice Ryhl
2023-07-13 3:28 ` Martin Rodriguez Reboredo [this message]
2023-07-15 13:38 ` Benno Lossin
2023-08-09 14:09 ` Andreas Hindborg (Samsung)
2023-08-22 9:31 ` Alice Ryhl
2023-08-23 8:40 ` Andreas Hindborg (Samsung)
2023-08-22 9:31 ` Alice Ryhl
2023-08-23 8:43 ` Andreas Hindborg (Samsung)
2023-08-23 10:34 ` Alice Ryhl
2023-08-23 16:09 ` Andreas Hindborg (Samsung)
2023-10-25 12:22 ` Ariel Miculas (amiculas)
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