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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=5392; i=markus.probst@posteo.de; h=from:subject:message-id; bh=G4tGnfVAqaeco11nDA1ti85WNH9PZHB0NXiR8QYpbZc=; b=owEBiQJ2/ZANAwAIATR2H/jnrUPSAcsmYgBq2fi9hJTIW2/b7GYx/qG8+qrmpUGpzTOV214X2 9EnH3XcPc+JAk8EAAEIADkWIQSCdBjE9KxY53IwxHM0dh/4561D0gUCatn4vRsUgAAAAAAEAA5t YW51MiwyLjUrMS4xMiwyLDIACgkQNHYf+OetQ9KZ9RAAtYSbzy9bH0ivF+grAtI69T4xmhXemP5 ril/7gOOv54hphYFAhHYG3t+HlMw8/DUThPKP027ThLHWZMosyPM+AOeOfUhtp3xgOWa7xPC++m Sb5cfZmq/ClJiPCNAzwQKDT48tcJ+/qotSvQ0Kr4SbZH5tZTCxnBaSunpxfgD2KaDjM77JOloq/ T0cyhXLJDKPl9TyKqLspc2NIu4VNO7Y1C5ujLYi8kIDUmuQrlxFic1kMxIX0Y+od+yi/K/KiYP+ qkbQ4vItpxUQ0W57ehdUaOIek9lrb7M6vcChcNcEgf5keVrgmD3J4sZkDcIweqKkYiav+QlcWTt mrZD0QqCRwLimqXTYr2GtsUWjze2Lrf3vr3lf4/bwucnHYmLqXoAPU+h/0vA+mtq8c3LOMLHDkf r5JxzwOH07hadrVdEvsWmRRr54sUqSBMrVDmbcdGKlYQegz4PK4qlEOThCaTAIoMc7OJeu5Za6r Lo51AiPpllIYd8QDO24Vdwa7OTtZcSVSxLhrC5WWRc32bAnu7qfli+HmuMOLwB7g5G2OryfZ0sp CRPJdnxrOFIjff5duofC11waL91rl51VKNvBRtW/bkbILKp7Nf1wry8uhPE0KZxAFK3OCKRdj9b wveyRAT3xLpoQGrof7pKxjh2hvQvH6b1X6v8AVer3ifqbH/G8uv0= 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 | 44 +++++++++++++++++++++++++++++++------ include/linux/serdev.h | 2 +- 3 files changed, 45 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..7d2d50d7e1a4 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; @@ -99,14 +103,23 @@ 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; } ret = tty->ops->open(serport->tty, NULL); @@ -128,25 +141,37 @@ static int ttyport_open(struct serdev_controller *ctrl) ktermios.c_cflag |= CLOCAL; tty_set_termios(tty, &ktermios); + mutex_lock(&serport->receive_lock); 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: +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 +179,8 @@ 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 +315,9 @@ 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