From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout02.posteo.de (mout02.posteo.de [185.67.36.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C968D336EC9 for ; Sun, 6 Sep 2026 15:55:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.67.36.66 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788710136; cv=none; b=fQ+ZaVnNRAE0jkOg8XwFfk+ldquk0pnOUDQuZ31bJQxykJv+Fuk2Beq3b4W/9m3KSJPqicm1gCUn9AX/50vue4ws0tU6Uq5nbFHr3GbUrWlSrwczNY2yPCybH2bKDfdNIg3TCUC7uzwp8e1VQ5PejLGZfdA+jEOkJNws0VKJNLY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788710136; c=relaxed/simple; bh=xmTFRFw7V/HU3JXIe69biF6uXSYP9tKIxk/FBu1sWo0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Mc6W+0gq/iYePhXECzSXMdQ0pIoU8o6I7DKrPasbBwAUPZ4340/Ok50iA4k4JjQJ1Fdx1I6SsEnLwVDDTehGeAJJruxohL4gqKJDPz3v50Vi/Faxjz3KrPO8C4eEF0ddo0ZL2ZgyS8KQIG7bo6plcb1oT4KukzMt3hDlugL4f8E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de; spf=pass smtp.mailfrom=posteo.de; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b=XH7qOOBp; arc=none smtp.client-ip=185.67.36.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=posteo.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=posteo.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=posteo.de header.i=@posteo.de header.b="XH7qOOBp" Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id C3D86240104 for ; Sun, 6 Sep 2026 17:55:32 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=1984.8680eb; t=1788710132; bh=UTm4yQVbwMpMizb1S87Kb2YZ7hCkc36LgIfvhH/1KKk=; h=From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:To:Cc:Autocrypt:OpenPGP:From; b=XH7qOOBpC/NsVJIV/1lslRF+cZu0Qgqh5zY5c0rr6/hKg1GBqqCgMOD/o5FMMjrLf Dg85S9T1QlZLYV/vE30BX3xjKL82ZVhC5wpSXqDZD4JxbCCB1pP3UEt7+BgJY68keQ maS54hrLJaHrjtoJDuAUuLzExy9ciJTtoAUOm33R+g7omu67wfsbpMMfoTvpNG5MYR Hp/0brIiJZNFEvmxa6SmxyZkyADNCz1YKPCnvQz4qkKqoUPGf2gHJQKOJd0CUXd/qi jImfzKsUGs6XicIBQFsii1Cpj2E/irtDENRSPgJjFSGlSoGXxQKHulRgRXYHokQ1L8 qzDitlh8g/EEA== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4hdFCh4dtpz6v3h; Sun, 6 Sep 2026 17:55:28 +0200 (CEST) From: Markus Probst Date: Sun, 06 Sep 2026 15:55:30 +0000 Subject: [PATCH 2/5] rust: serdev: Replace `active` mutex with receive pause Precedence: bulk X-Mailing-List: linux-kernel@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: <20260906-rust_serdev_probe_refactor-v1-2-69cdae0074ec@posteo.de> References: <20260906-rust_serdev_probe_refactor-v1-0-69cdae0074ec@posteo.de> In-Reply-To: <20260906-rust_serdev_probe_refactor-v1-0-69cdae0074ec@posteo.de> To: Ayush Singh , Johan Hovold , Alex Elder , 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?= , Eric Biggers , Ard Biesheuvel , Lorenzo Stoakes , Vlastimil Babka , "Liam R. Howlett" , Uladzislau Rezki , Jiri Slaby , "Rafael J. Wysocki" Cc: greybus-dev@lists.linaro.org, linux-serial@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, Markus Probst , Sashiko Bot X-Developer-Signature: v=1; a=openpgp-sha256; l=6499; i=markus.probst@posteo.de; h=from:subject:message-id; bh=xmTFRFw7V/HU3JXIe69biF6uXSYP9tKIxk/FBu1sWo0=; b=owEBiQJ2/ZANAwAIATR2H/jnrUPSAcsmYgBqnYzqmas2+Lg+oqHbSUW0zD7px/TGT5hvRpANM zGexL3WQhuJAk8EAAEIADkWIQSCdBjE9KxY53IwxHM0dh/4561D0gUCap2M6hsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMiwyLDIACgkQNHYf+OetQ9Ileg//dOrkcD6wllXJnVtCsKWLO6xbGHv9tq6 zRNa4+WZP9GI9bPEoiAF37X2fP/4F7vOHjLt+hJTe8XHvlMI8vq1AGHS72HmTFMNYcI4Tnw648Q kJ5ywnBWCLePtvrQrY6CGQ629k9HSl55jtAIXfvLE4A65cBfBfdu0KnU542TKasxRWAyzD0sNY8 CqIsCpJoVSxFcfnaXuFVqn1yWP3+XEUcRVj9IJ4ZK4tqzJJWMRn/GJcQMg+BTOoRA6RVxOaEurQ jWR8e+8i7rmFulKnn0q/gndK0vRFp/uiKRqnFDGaASRqQ3S0eYcbAHbI1MqxETeku7UH/hdLdeL FmE0oLEs5R7bPyp/jlWKm5qgxjMcAuYVAjt2/zzjrwP3sdXwSUhEen6jgWtlQUZmqRkilSBxOfl Th2jCtd3ffn/YApEkMBlYUfMXztAbnQCn8fMQlHyR7meYIPt1Fm8FCiEV5FFK5m0IfiL55xji2P RbXb7yj0DsEyX6KTKZDc89zmUQJ2eee11YS/tHi/zjuuiFFr2ItSfj5w3tyjU9+sC44IQTKHnAD DBzF7xeLBGrnH+3W8mlZxVANx2W02rsr9aukwX/UkF0SpmtjH4dmRVbXw2lKN6XRCGtchXsRInj ayKCOTsoILiL/mAxXzdU+hKI7W/raHrX/8BKK0sx/qkBHzDVsZ4o= X-Developer-Key: i=markus.probst@posteo.de; a=openpgp; fpr=827418C4F4AC58E77230C47334761FF8E7AD43D2 Autocrypt: addr=markus.probst@posteo.de; prefer-encrypt=mutual; keydata=xsFNBGiDvXgBEADAXUceKafpl46S35UmDh2wRvvx+UfZbcTjeQOlSwKP7YVJ4JOZrVs93qReNLkO WguIqPBxR9blQ4nyYrqSCV+MMw/3ifyXIm6Pw2YRUDg+WTEOjTixRCoWDgUj1nOsvJ9tVAm76Ww+ /pAnepVRafMID0rqEfD9oGv1YrfpeFJhyE2zUw3SyyNLIKWD6QeLRhKQRbSnsXhGLFBXCqt9k5JA RhgQof9zvztcCVlT5KVvuyfC4H+HzeGmu9201BVyihJwKdcKPq+n/aY5FUVxNTgtI9f8wIbmfAja oT1pjXSp+dszakA98fhONM98pOq723o/1ZGMZukyXFfsDGtA3BB79HoopHKujLGWAGskzClwTjRQ xBqxh/U/lL1pc+0xPWikTNCmtziCOvv0KA0arDOMQlyFvImzX6oGVgE4ksKQYbMZ3Ikw6L1Rv1J+ FvN0aNwOKgL2ztBRYscUGcQvA0Zo1fGCAn/BLEJvQYShWKeKqjyncVGoXFsz2AcuFKe1pwETSsN6 OZncjy32e4ktgs07cWBfx0v62b8md36jau+B6RVnnodaA8++oXl3FRwiEW8XfXWIjy4umIv93tb8 8ekYsfOfWkTSewZYXGoqe4RtK80ulMHb/dh2FZQIFyRdN4HOmB4FYO5sEYFr9YjHLmDkrUgNodJC XCeMe4BO4iaxUQARAQABzRdtYXJrdXMucHJvYnN0QHBvc3Rlby5kZcLBkQQTAQgAOxYhBIJ0GMT0 rFjncjDEczR2H/jnrUPSBQJog714AhsDBQsJCAcCAiICBhUKCQgLAgQWAgMBAh4HAheAAAoJEDR2 H/jnrUPSgdkQAISaTk2D345ehXEkn5z2yUEjaVjHIE7ziqRaOgn/QanCgeTUinIv6L6QXUFvvIfH 1OLPwQ1hfvEg9NnNLyFezWSy6jvoVBTIPqicD/r3FkithnQ1IDkdSjrarPMxJkvuh3l7XZHo49GV HQ8i5zh5w4YISrcEtE99lJisvni2Jqx7we5tey9voQFDyM8jxlSWv3pmoUTCtBkX/eKHJXosgsuS B4TGDCVPOjla/emI5c9MhMG7O4WEEmoSdPbmraPw66YZD6uLyhV4DPHbiDWRzXWnClHSyjB9rky9 lausFxogvu4l9H+KDsXIadNDWdLdu1/enS/wDd9zh5S78rY2jeXaG4mnf4seEKamZ7KQ6FIHrcyP ezdDzssPQcTQcGRMQzCn6wP3tlGk7rsfmyHMlFqdRoNNv+ZER/OkmZFPW655zRfbMi0vtrqK2Awm 9ggobb1oktfd9PPNXMUY+DNVlgR2G7jLnenSoQausLUm0pHoNE8TWFv851Y6SOYnvn488sP1Tki5 F3rKwclawQFHUXTCQw+QSh9ay8xgnNZfH+u9NY7w3gPoeKBOAFcBc2BtzcgekeWS8qgEmm2/oNFV G0ivPQbRx8FjRKbuF7g3YhgNZZ0ac8FneuUtJ2PkSIFTZhaAiC0utvxk0ndmWFiW4acEkMZGrLaM L2zWNjrqwsD2zsFNBGiDvXgBEADCXQy1n7wjRxG12DOVADawjghKcG+5LtEf31WftHKLFbp/HArj BhkT6mj+CCI1ClqY+FYU5CK/s0ScMfLxRGLZ0Ktzawb78vOgBVFT3yB1yWBTewsAXdqNqRooaUNo 8cG/NNJLjhccH/7PO/FWX5qftOVUJ/AIsAhKQJ18Tc8Ik73v427EDxuKb9mTAnYQFA3Ev3hAiVbO 6Rv39amVOfJ8sqwiSUGidj2Fctg2aB5JbeMln0KCUbTD1LhEFepeKypfofAXQbGwaCjAhmkWy/q3 IT1mUrPxOngbxdRoOx1tGUC0HCMUW1sFaJgQPMmDcR0JGPOpgsKnitsSnN7ShcCr1buel7vLnUMD +TAZ5opdoF6HjAvAnBQaijtK6minkrM0seNXnCg0KkV8xhMNa6zCs1rq4GgjNLJue2EmuyHooHA4 7JMoLVHcxVeuNTp6K2+XRx0Pk4e2Lj8IVy9yEYyrywEOC5XRW37KJjsiOAsumi1rkvM7QREWgUDe Xs0+RpxI3QrrANh71fLMRo7LKRF3Gvw13NVCCC9ea20P4PwhgWKStkwO2NO+YJsAoS1QycMi/vKu 0EHhknYXamaSV50oZzHKmX56vEeJHTcngrM8R1SwJCYopCx9gkz90bTVYlitJa5hloWTYeMD7FNj Y6jfVSzgM/K4gMgUNDW/PPGeMwARAQABwsF2BBgBCAAgFiEEgnQYxPSsWOdyMMRzNHYf+OetQ9IF AmiDvXgCGwwACgkQNHYf+OetQ9LHDBAAhk+ab8+WrbS/b1/gYW3q1KDiXU719nCtfkUVXKidW5Ec Idlr5HGt8ilLoxSWT2Zi368iHCXS0WenGgPwlv8ifvB7TOZiiTDZROZkXjEBmU4nYjJ7GymawpWv oQwjMsPuq6ysbzWtOZ7eILx7cI0FjQeJ/Q2baRJub0uAZNwBOxCkAS6lpk5Fntd2u8CWmDQo4SYp xeuQ+pwkp0yEP30RhN2BO2DXiBEGSZSYh+ioGbCHQPIV3iVj0h6lcCPOqopZqyeCfigeacBI0nvN jHWz/spzF3+4OS+3RJvoHtAQmProxyGib8iVsTxgZO3UUi4TSODeEt0i0kHSPY4sCciOyXfAyYoD DFqhRjOEwBBxhr+scU4C1T2AflozvDwq3VSONjrKJUkhd8+WsdXxMdPFgBQuiKKwUy11mz6KQfcR wmDehF3UaUoxa+YIhWPbKmycxuX/D8SvnqavzAeAL1OcRbEI/HsoroVlEFbBRNBZLJUlnTPs8ZcU 4+8rq5YX1GUrJL3jf6SAfSgO7UdkEET3PdcKFYtS+ruV1Cp5V0q4kCfI5jk25iiz8grM2wOzVSsc l1mEkhiEPH87HP0whhb544iioSnumd3HJKL7dzhRegsMizatupp8D65A2JziW0WKopa1iw9fti3A aBeNN4ijKZchBXHPgVx+YtWRHfcm4l8= OpenPGP: url=https://posteo.de/keys/markus.probst@posteo.de.asc; preference=encrypt There are currently 2 race conditions: - in probe if `Driver::probe` returns Err - in unbind . In those cases the driver data will be set to NULL before the serdev device was closed. If data is received while the driver data is dropped, the `receive_buf_callback` might try to access the `active` mutex on a null pointer. Removing the need for `receive_buf_callback` to lock the `active` mutex fixes these. Fixes: 99f59aa82341 ("rust: add basic serial device bus abstractions") Reported-by: Sashiko Bot Closes: https://lore.kernel.org/linux-serial/20260905000836.C8FC91F00A3D@smtp.kernel.org/ Closes: https://lore.kernel.org/linux-serial/20260903222159.70A911F000E9@smtp.kernel.org/ Signed-off-by: Markus Probst --- rust/kernel/serdev.rs | 60 ++++++++++++--------------------------------------- 1 file changed, 14 insertions(+), 46 deletions(-) diff --git a/rust/kernel/serdev.rs b/rust/kernel/serdev.rs index 17ca504b7f8d..c16d6593a8d2 100644 --- a/rust/kernel/serdev.rs +++ b/rust/kernel/serdev.rs @@ -13,13 +13,9 @@ to_result, VTABLE_DEFAULT_ERROR, // }, - new_mutex, of, prelude::*, - sync::{ - aref::AlwaysRefCounted, - Mutex, // - }, + sync::aref::AlwaysRefCounted, time::Jiffies, types::{ Opaque, @@ -103,40 +99,11 @@ 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, } #[pinned_drop] impl PinnedDrop for PrivateData<'_, T> { fn drop(self: Pin<&mut Self>) { - let mut active = self.active.lock(); - if *active { - // SAFETY: - // - We have exclusive access to `self.driver`. - // - `self.driver` is guaranteed to be initialized. - unsafe { (*self.driver.get()).assume_init_drop() }; - *active = false; - } - drop(active); - // SAFETY: We have exclusive access to `self.open`. if unsafe { *self.open.get() } { // SAFETY: `self.sdev.as_raw()` is guaranteed to be a pointer to a valid @@ -170,7 +137,6 @@ extern "C" fn probe_callback(sdev: *mut bindings::serdev_device) -> kernel::ffi: sdev: &**sdev, driver: MaybeUninit::>::zeroed().into(), open: false.into(), - active <- new_mutex!(false), }))?; // SAFETY: We just set drvdata to `PrivateData<'_, T>`. let private_data = unsafe { sdev.as_ref().drvdata_borrow::>() }; @@ -178,11 +144,12 @@ extern "C" fn probe_callback(sdev: *mut bindings::serdev_device) -> kernel::ffi: // SAFETY: We just set drvdata to `PrivateData<'_, T>`. drop(unsafe { sdev.as_ref().drvdata_obtain::>() }); }); - let mut active = private_data.active.lock(); - // SAFETY: `sdev.as_raw()` is guaranteed to be a valid pointer to `serdev_device`. unsafe { bindings::serdev_device_set_client_ops(sdev.as_raw(), Self::OPS) }; + // SAFETY: `sdev.as_raw()` is guaranteed to be a valid pointer to `serdev_device`. + unsafe { bindings::serdev_device_pause_rx(sdev.as_raw()) }; + // SAFETY: The serial device bus only ever calls the probe callback with a valid pointer // to a `serdev_device`. to_result(unsafe { bindings::serdev_device_open(sdev.as_raw()) })?; @@ -199,12 +166,12 @@ extern "C" fn probe_callback(sdev: *mut bindings::serdev_device) -> kernel::ffi: // - `private_data.driver` is pinned. let result = unsafe { pin_init::raw_try_init(driver.as_mut_ptr(), data) }; - *active = result.is_ok(); - - drop(active); - result.map(|()| { private_data.dismiss(); + + // SAFETY: `sdev.as_raw()` is guaranteed to be a valid pointer to `serdev_device`. + unsafe { bindings::serdev_device_resume_rx(sdev.as_raw()) }; + 0 }) }) @@ -231,6 +198,12 @@ extern "C" fn remove_callback(sdev: *mut bindings::serdev_device) { let data_pinned = unsafe { Pin::new_unchecked(data.assume_init_ref()) }; T::unbind(sdev, data_pinned); + + // SAFETY: `sdev.as_raw()` is guaranteed to be a valid pointer to `serdev_device`. + unsafe { bindings::serdev_device_pause_rx(sdev.as_raw()) }; + + // SAFETY: We already established that `data` is guaranteed to be initialized. + unsafe { data.assume_init_drop() }; } extern "C" fn receive_buf_callback( @@ -248,11 +221,6 @@ extern "C" fn receive_buf_callback( // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called // and stored a `Pin>>`. let private_data = unsafe { sdev.as_ref().drvdata_borrow::>() }; - let active = private_data.active.lock(); - - if !*active { - return length; - } // SAFETY: No one has exclusive access to `private_data.driver`. let data = unsafe { &*private_data.driver.get() }; -- 2.55.0