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Wysocki" , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Alexander Viro , Christian Brauner , Jan Kara , Lorenzo Stoakes , "Liam R. Howlett" , Viresh Kumar , Nishanth Menon , Stephen Boyd , Bjorn Helgaas , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Paul Moore , Serge Hallyn , Asahi Lina , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-pm@vger.kernel.org, linux-pci@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [PATCH v13 2/4] rust: `AlwaysRefCounted` is renamed to `RefCounted`. In-Reply-To: <20251201160030.6956a834.gary@garyguo.net> References: <20251117-unique-ref-v13-0-b5b243df1250@pm.me> <20251117-unique-ref-v13-2-b5b243df1250@pm.me> <20251201160030.6956a834.gary@garyguo.net> Date: Mon, 02 Feb 2026 10:48:39 +0100 Message-ID: <87wm0vpjbc.fsf@t14s.mail-host-address-is-not-set> MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 313B218000B X-Stat-Signature: enx1w3713fujtuerjpncuah87z1qxw6f X-Rspam-User: X-HE-Tag: 1770026798-697957 X-HE-Meta: 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 BKHJjmDf f1L2fgYmHWShdgXUfJDgJY8M3k4oyZYS5fwEtiY28w6vW1WLWpZhE0ZSc/ukk9YEgHJZ52uZF5e5KQfIH8An7R/iLFa+XKFNlBlyNUDCnSMI2eBeYDrL8Eul2H6D+ZjC7SFvGqhEqFdfSZ60tD69PxnUwULlXsPTLOEP+g8mU+rUXnbAUT2dVyWehU2LZG+ck57SRp05eGQT/K7oivL8EZw0FDlEpUXi8xJnOR/oHJmy+Dt0fZ3bgezO32C9Ticso1cZud6kN4tu+zBrDG4oSdAWVAqQpaVR9o3UJTYRfmQkfM+Q= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Gary Guo writes: > On Mon, 17 Nov 2025 10:07:57 +0000 > Oliver Mangold wrote: > >> `AlwaysRefCounted` will become a marker trait to indicate that it is >> allowed to obtain an `ARef` from a `&T`, which cannot be allowed for >> types which are also Ownable. > > The message needs a rationale for making the change rather than relying > on the reader to deduce so. > > For example: > > There are types where it may both be referenced counted in some > cases and owned in other. In such cases, obtaining `ARef` > from `&T` would be unsound as it allows creation of `ARef` > copy from `&Owned`. > > Therefore, we split `AlwaysRefCounted` into `RefCounted` (which > `ARef` would require) and a marker trait to indicate that > the type is always reference counted (and not `Ownable`) so the > `&T` -> `ARef` conversion is possible. Thanks, I'll mix this in with the one I sent to Daniel. Best regards, Andreas Hindborg