From c823fe2d3f23ed090e36ce39beed4c448298bd2f Mon Sep 17 00:00:00 2001
From: Michael Stapelberg <michael@stapelberg.de>
Date: Sat, 3 Apr 2021 19:02:13 +0200
Subject: [PATCH] ChibiOS USB driver: prevent deadlock with CONSOLE_ENABLE =
yes
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 cc0ce7600fc..eb72f8ff6dc 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); }