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AJvYcCX7pzi1HXY6zrifmTIWXOq8czFmanbzAoo2ojA/oWQ66+5tO0492bmNCQE2ZujR3CLVXY+CTHQPdt5fSPyeUQ==@vger.kernel.org X-Gm-Message-State: AOJu0YzOrmTS7nfCr/bWnd1QvNjw04JPr0x258xYWVnQpgcp0t0pAzTX Yb3X4ltblZM2mbBRQ/fa/HZtL7AoYxGpJDkCJEsgql4GxI663ugoWs/LLaTmlm7keNJJvgu+GId bFRVxiKI8vg/LPdBBQw== X-Google-Smtp-Source: AGHT+IETm21fGX6EDVvCILpaGt3LhqUeqy+mLvIfJDOMBQXcjhqGiJe96JoM5T9wMnLNcUF5CHiClrXvuov77ts= X-Received: from wmsd10.prod.google.com ([2002:a05:600c:3aca:b0:451:d70f:eb87]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6000:2209:b0:3a4:e56a:48c5 with SMTP id ffacd0b85a97d-3a51d8ffd92mr1637145f8f.16.1749030040535; Wed, 04 Jun 2025 02:40:40 -0700 (PDT) Date: Wed, 4 Jun 2025 09:40:38 +0000 In-Reply-To: <3eef5777-9190-4782-8433-7b6ad4b9acd3@gmail.com> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250530-b4-rust_miscdevice_registrationdata-v4-0-d313aafd7e59@gmail.com> <20250530-b4-rust_miscdevice_registrationdata-v4-2-d313aafd7e59@gmail.com> <3eef5777-9190-4782-8433-7b6ad4b9acd3@gmail.com> Message-ID: Subject: Re: [PATCH v4 2/3] rust: miscdevice: add additional data to MiscDeviceRegistration From: Alice Ryhl To: Christian Schrefl Cc: Benno Lossin , Miguel Ojeda , Danilo Krummrich , Alex Gaynor , Boqun Feng , Gary Guo , "=?utf-8?B?QmrDtnJu?= Roy Baron" , Andreas Hindborg , Trevor Gross , Arnd Bergmann , Greg Kroah-Hartman , Lee Jones , Daniel Almeida , "Gerald =?utf-8?Q?Wisb=C3=B6ck?=" , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" On Mon, Jun 02, 2025 at 11:16:33PM +0200, Christian Schrefl wrote: > On 31.05.25 2:23 PM, Benno Lossin wrote: > > On Fri May 30, 2025 at 10:46 PM CEST, Christian Schrefl wrote: > >> + unsafe { core::ptr::drop_in_place(self.data.get()) }; > >> } > >> } > >> > >> @@ -109,6 +135,13 @@ pub trait MiscDevice: Sized { > >> /// What kind of pointer should `Self` be wrapped in. > >> type Ptr: ForeignOwnable + Send + Sync; > >> > >> + /// The additional data carried by the [`MiscDeviceRegistration`] for this [`MiscDevice`]. > >> + /// If no additional data is required than the unit type `()` should be used. > >> + /// > >> + /// This data can be accessed in [`MiscDevice::open()`] using > >> + /// [`MiscDeviceRegistration::data()`]. > >> + type RegistrationData: Sync; > > > > Why do we require `Sync` here? > > Needed for `MiscDeviceRegistration` to be `Send`, see response above. Even if `MiscDeviceRegistration` is non-Send, the registration data must still be Sync. The f_ops->open callback can *always* be called from any thread no matter what we do here, so the data it gives you access must always be Sync no matter what. Alice