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 BD0C65AA664 for ; Fri, 16 Oct 2026 18:00:42 +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=1792173644; cv=none; b=qEfwlK2k9mPV3gfpl5JxgTAuEVNuxZ7Esj5zv2HsrAqdchUvt+U47YJRYPYuwD8Ojmv4R2TEDpOUEW4FG1gqgOqi6C6E6uOGkw4jzYZ1KYC9aTyUzSwkymE/Mhs0PcmeG2UOq63Jf78LUUrHS6Q+0GN/QL8Cd7LG1jrSlvdxyfo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792173644; c=relaxed/simple; bh=TcY/fwsvwWTyZGT4Q+t3XjtTaR0BxABgEPLqqJD8Ol0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=a+N2hmhO5cuYwCYgjDfUWxuC+PPCCnRm6eU2VhdWZPaSpZ7rKtqk2bN8AucV4Xf9jdKdSlr0GglCPSa2hpbFcLsc6ShmcTivusbJYRcYYnapJxmwSC2MFeg4JGUsRxIvnGfxBp94lBe/4xJ4kXaa0pzKTg2gZagSJtCVWF5/jAQ= 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=a4M42SlC; 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="a4M42SlC" Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id A4C6C240112 for ; Fri, 16 Oct 2026 20:00:33 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=posteo.de; s=1984.8680eb; t=1792173633; bh=ICDgGJRQLw9lW5mPqSb+6EHYmo3Fca+zvavA2Drr16I=; h=From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:To:Cc:Autocrypt:OpenPGP:From; b=a4M42SlC1KJZB/fXI+tb/XXozQnO9f1IjIx8CvHyVBrPca0xE15mitrCjPyr62yg0 jXsbgQum8qab2F2gUumqghlIl6GntYaWzM8fM5FJ4QA3KciiYCIpLIkkiIImNTteqP 4d+SWRHAaR0mhjmI02eN4w8tlcR4VPv/R0WWZg+NrqhDHAUbS0GAOSKRvwrOtQo8Gj Oqsl5RhQYQtXpmnXWg7AN0s8zlzdFgZgzdJV25G4XHBXK1+WF64eI7lOS+P0ZEnvmA 9U3SAALSt88l65K6e27GJPHmMFlESrGFo4Q3xkU4DG049FHKpHdTHVAFb8ytrYLlq7 PySZL5W1vYtVA== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4j5t5T49Lqz9rxG; Fri, 16 Oct 2026 20:00:29 +0200 (CEST) From: Markus Probst Date: Fri, 16 Oct 2026 18:00:32 +0000 Subject: [PATCH v4 1/4] tty: serdev: Add mutex lock 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: <20261016-rust_serdev_probe_refactor-v4-1-46832e034757@posteo.de> References: <20261016-rust_serdev_probe_refactor-v4-0-46832e034757@posteo.de> In-Reply-To: <20261016-rust_serdev_probe_refactor-v4-0-46832e034757@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 X-Developer-Signature: v=1; a=openpgp-sha256; l=5400; i=markus.probst@posteo.de; h=from:subject:message-id; bh=TcY/fwsvwWTyZGT4Q+t3XjtTaR0BxABgEPLqqJD8Ol0=; b=owEBiQJ2/ZANAwAIATR2H/jnrUPSAcsmYgBq0mY4iygoYy5F91Yd8Oh74dJE6qds/6G2jV13c tGbZwWFx/qJAk8EAAEIADkWIQSCdBjE9KxY53IwxHM0dh/4561D0gUCatJmOBsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMiwyLDIACgkQNHYf+OetQ9JJoxAAh/QgZidUVSxiALIfcJ2P5+8jSXCoCXr 6ia8cj4a5jIvH3ZAPlEo3cDcijnBPwG5nf594ZQ0hMW68sL881OcDzro38kcF9XLnOM1oBVJQrg j835uti6ka9HDnS878KK66r0A+H9iS/so+T8XmU3vDk8rACkccn7p8Smew3lkyRNUi1MFnudJLj ErGDPTChcIimout2DUDlwKkZf392+MuiywNFiykusGCKeS53Ai91RQ1oqhiPgRpY7hc4tJJJLbr 3XlfsDGrXOK8XTLPaNWiUgKs4XCpUx2a2P+yhcUQpCpPVsh5jewFA8ii1R29g25qy8CxT/5ZI6m NqNo3a64j5j3gOG+z6spaO+CuskZ/5rWDGG2QvSYhu6qBjTooy6Jtel/WkJGeWnR4gDFOJAxHTS 77sWR0ffrO9GGRkNS8zjaZeXDuWudlD3/cstbp4nWIp2/NYBlM/jl0Y6KJATkal+He4UQDXGisg +MS+zLQS/OIg/+ojyPuQtnt5rJx2itW3C0klL90SWpZDMhjxUn6sD7IDih7WYCcCNZs2meuo7PR 4tyqGOnM68zeNs0s5guD+YnYBtcox4BYV8QQTBMFcPVLgtHwbFzzAKwL8OJH/t0F+JA1WT/nTLq DwZxMA5roK8vmrdz+V5gv6xMjU0SENyLUDlNA8H6YHhRWcosu9kk= 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 Besides more predictable behaviour, this allows for several hardened behaviour changes: Return -EALREADY in `serdev_device_open` if the device is already open instead of causing undefined behaviour. Allow calling `serdev_device_close`, even if the device is already closed instead of causing a null pointer dereference. If the device is left open by the driver after remove, close it and warn instead of leaving it in a invalid state. Signed-off-by: Markus Probst --- drivers/tty/serdev/core.c | 10 +++++--- drivers/tty/serdev/serdev-ttyport.c | 46 +++++++++++++++++++++++++++++++------ include/linux/serdev.h | 2 +- 3 files changed, 47 insertions(+), 11 deletions(-) diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c index 7500efcdfc21..77e8e1d4d2a6 100644 --- a/drivers/tty/serdev/core.c +++ b/drivers/tty/serdev/core.c @@ -142,6 +142,11 @@ void serdev_device_remove(struct serdev_device *serdev) struct serdev_controller *ctrl = serdev->ctrl; device_unregister(&serdev->dev); + + /* Warn if driver did not close the serial device. */ + if (ctrl->ops->close && WARN_ON(ctrl->ops->close(ctrl))) + pm_runtime_put(&ctrl->dev); + ctrl->serdev = NULL; } EXPORT_SYMBOL_GPL(serdev_device_remove); @@ -181,9 +186,8 @@ void serdev_device_close(struct serdev_device *serdev) if (!ctrl || !ctrl->ops->close) return; - pm_runtime_put(&ctrl->dev); - - ctrl->ops->close(ctrl); + if (ctrl->ops->close(ctrl)) + pm_runtime_put(&ctrl->dev); } EXPORT_SYMBOL_GPL(serdev_device_close); diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c index bab1b143b8a6..125a17a0bea5 100644 --- a/drivers/tty/serdev/serdev-ttyport.c +++ b/drivers/tty/serdev/serdev-ttyport.c @@ -16,6 +16,8 @@ struct serport { struct tty_driver *tty_drv; int tty_idx; unsigned long flags; + struct mutex lock; /* lock preventing modification of flags */ + struct mutex receive_lock; /* lock preventing execution of serdev_controller_receive_buf */ }; /* @@ -29,6 +31,8 @@ static size_t ttyport_receive_buf(struct tty_port *port, const u8 *cp, struct serport *serport = serdev_controller_get_drvdata(ctrl); size_t ret; + guard(mutex)(&serport->receive_lock); + if (!test_bit(SERPORT_ACTIVE, &serport->flags)) return 0; @@ -99,16 +103,27 @@ static int ttyport_open(struct serdev_controller *ctrl) struct ktermios ktermios; int ret; + mutex_lock(&serport->lock); + + if (test_bit(SERPORT_ACTIVE, &serport->flags)) { + ret = -EALREADY; + goto err_flags_unlock; + } + tty = tty_init_dev(serport->tty_drv, serport->tty_idx); - if (IS_ERR(tty)) - return PTR_ERR(tty); + if (IS_ERR(tty)) { + ret = PTR_ERR(tty); + goto err_flags_unlock; + } serport->tty = tty; if (!tty->ops->open || !tty->ops->close) { ret = -ENODEV; - goto err_unlock; + goto err_tty_unlock; } + mutex_lock(&serport->receive_lock); + ret = tty->ops->open(serport->tty, NULL); if (ret) goto err_close; @@ -130,23 +145,35 @@ static int ttyport_open(struct serdev_controller *ctrl) set_bit(SERPORT_ACTIVE, &serport->flags); + mutex_unlock(&serport->receive_lock); + mutex_unlock(&serport->lock); + return 0; err_close: tty->ops->close(tty, NULL); -err_unlock: + mutex_unlock(&serport->receive_lock); +err_tty_unlock: tty_unlock(tty); tty_release_struct(tty, serport->tty_idx); +err_flags_unlock: + mutex_unlock(&serport->lock); return ret; } -static void ttyport_close(struct serdev_controller *ctrl) +static bool ttyport_close(struct serdev_controller *ctrl) { struct serport *serport = serdev_controller_get_drvdata(ctrl); - struct tty_struct *tty = serport->tty; + struct tty_struct *tty; + + guard(mutex)(&serport->lock); - clear_bit(SERPORT_ACTIVE, &serport->flags); + tty = serport->tty; + + scoped_guard(mutex, &serport->receive_lock) + if (!__test_and_clear_bit(SERPORT_ACTIVE, &serport->flags)) + return false; tty_lock(tty); if (tty->ops->close) @@ -154,6 +181,8 @@ static void ttyport_close(struct serdev_controller *ctrl) tty_unlock(tty); tty_release_struct(tty, serport->tty_idx); + + return true; } static unsigned int ttyport_set_baudrate(struct serdev_controller *ctrl, unsigned int speed) @@ -288,6 +317,9 @@ struct device *serdev_tty_port_register(struct tty_port *port, port->client_ops = &client_ops; port->client_data = ctrl; + mutex_init(&serport->lock); + mutex_init(&serport->receive_lock); + ret = serdev_controller_add(ctrl); if (ret) goto err_reset_data; diff --git a/include/linux/serdev.h b/include/linux/serdev.h index b6c3d957ec15..0f4e81c0950d 100644 --- a/include/linux/serdev.h +++ b/include/linux/serdev.h @@ -81,7 +81,7 @@ struct serdev_controller_ops { ssize_t (*write_buf)(struct serdev_controller *, const u8 *, size_t); void (*write_flush)(struct serdev_controller *); int (*open)(struct serdev_controller *); - void (*close)(struct serdev_controller *); + bool (*close)(struct serdev_controller *); void (*set_flow_control)(struct serdev_controller *, bool); int (*set_parity)(struct serdev_controller *, enum serdev_parity); unsigned int (*set_baudrate)(struct serdev_controller *, unsigned int); -- 2.55.0