From 7d953332e0d7c0394c607156bf4099881bdf3f43 Mon Sep 17 00:00:00 2001 From: Michael Stapelberg Date: Sat, 10 Apr 2021 17:03:38 +0200 Subject: [PATCH] ChibiOS USB driver: prevent deadlock with CONSOLE_ENABLE = yes (#12472) Before this commit, attaching an ARM-based (i.e. ChibiOS-based) keyboard that uses CONSOLE_ENABLE = yes and produces debug messages would deadlock the keyboard unless one was running hid_listen. With this commit, dead-locking writes to the queue are detected and prevented. fixes #5631 --- tmk_core/protocol/chibios/usb_driver.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/tmk_core/protocol/chibios/usb_driver.c b/tmk_core/protocol/chibios/usb_driver.c index cc0ce7600..eb72f8ff6 100644 --- a/tmk_core/protocol/chibios/usb_driver.c +++ b/tmk_core/protocol/chibios/usb_driver.c @@ -80,7 +80,19 @@ static bool qmkusb_start_receive(QMKUSBDriver *qmkusbp) { * Interface implementation. */ -static size_t _write(void *ip, const uint8_t *bp, size_t n) { return obqWriteTimeout(&((QMKUSBDriver *)ip)->obqueue, bp, n, TIME_INFINITE); } +static size_t _write(void *ip, const uint8_t *bp, size_t n) { + output_buffers_queue_t *obqueue = &((QMKUSBDriver *)ip)->obqueue; + chSysLock(); + const bool full = obqIsFullI(obqueue); + chSysUnlock(); + if (full || bqIsSuspendedX(obqueue)) { + /* Discard any writes while the queue is suspended or full, i.e. the hidraw + interface is not open. If we tried to send with an infinite timeout, we + would deadlock the keyboard otherwise. */ + return -1; + } + return obqWriteTimeout(obqueue, bp, n, TIME_INFINITE); +} static size_t _read(void *ip, uint8_t *bp, size_t n) { return ibqReadTimeout(&((QMKUSBDriver *)ip)->ibqueue, bp, n, TIME_INFINITE); }