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Sat, 18 Jul 2026 14:47:49 +0200 (CEST) From: Markus Probst Date: Sat, 18 Jul 2026 12:47:49 +0000 Subject: [PATCH v2 3/4] rust: serdev: document `PrivateData::active` Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260718-rust_serdev_fixes-v2-3-e5214e03de13@posteo.de> References: <20260718-rust_serdev_fixes-v2-0-e5214e03de13@posteo.de> In-Reply-To: <20260718-rust_serdev_fixes-v2-0-e5214e03de13@posteo.de> To: Greg Kroah-Hartman , Miguel Ojeda , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , =?utf-8?q?Onur_=C3=96zkan?= Cc: linux-serial@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Markus Probst X-Developer-Signature: v=1; a=openpgp-sha256; l=1821; i=markus.probst@posteo.de; 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preference=encrypt Gary pointed out that it isn't clear for what the mutex is used for, thus adding documentation comments for it. Suggested-by: Gary Guo Link: https://lore.kernel.org/rust-for-linux/DK0SX3P5K1J6.1OV4ETJMXW83R@garyguo.net/ Signed-off-by: Markus Probst --- rust/kernel/serdev.rs | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/rust/kernel/serdev.rs b/rust/kernel/serdev.rs index 79d61c6ceeec..a78dfa6e2c27 100644 --- a/rust/kernel/serdev.rs +++ b/rust/kernel/serdev.rs @@ -132,6 +132,23 @@ pub struct PrivateData<'bound, T: Driver> { #[pin] driver: UnsafeCell>>, open: UnsafeCell, + /// Whether `receive_buf_callback` is allowed to call `Driver::receive`. + /// + /// If locked, the receive_buf_callback will be blocked on data reception. + /// This is the case while the driver is being probed or while [`PrivateData`] is being dropped. + /// This is necessary, because we need to open the serdev device before the driver has been + /// probed in order to allow it to be configured, which allows `receive_buf_callback` to be + /// called. Thus we need to block data until probe completes and the driver data becomes + /// initialized. + /// + /// If unlocked and true, the receive_buf_callback will forward the data to + /// `Driver::receive`. This is the normal state of operation. + /// + /// If unlocked and false, the receive_buf_callback will throw away the data. + /// This is only the case, if the serdev device is open and + /// - the driver returned an error in probe + /// or + /// - the driver data already has been dropped, because it was unbound. #[pin] active: Mutex, } -- 2.54.0