@@ -19,6 +19,7 @@
#include <linux/console.h>
#include <linux/vt_kern.h>
#include <linux/input.h>
+#include <linux/irq_work.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/serial_core.h>
@@ -48,6 +49,25 @@ static struct kgdb_io kgdboc_earlycon_io_ops;
static int (*earlycon_orig_exit)(struct console *con);
#endif /* IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */
+/*
+ * When we leave the debug trap handler we need to reset the keyboard status
+ * (since the original keyboard state gets partially clobbered by kdb use of
+ * the keyboard).
+ *
+ * The path to deliver the reset is somewhat circuitous.
+ *
+ * To deliver the reset we register an input handler, reset the keyboard and
+ * then deregister the input handler. However, to get this done right, we do
+ * have to carefully manage the calling context because we can only register
+ * input handlers from task context.
+ *
+ * In particular we need to trigger the action from the debug trap handler with
+ * all its NMI and/or NMI-like oddities. To solve this the kgdboc trap exit code
+ * (the "post_exception" callback) uses irq_work_queue(), which is NMI-safe, to
+ * schedule a callback from a hardirq context. From there we have to defer the
+ * work again, this time using schedule_work(), to get a callback using the
+ * system workqueue, which runs in task context.
+ */
#ifdef CONFIG_KDB_KEYBOARD
static int kgdboc_reset_connect(struct input_handler *handler,
struct input_dev *dev,
@@ -99,10 +119,17 @@ static void kgdboc_restore_input_helper(struct work_struct *dummy)
static DECLARE_WORK(kgdboc_restore_input_work, kgdboc_restore_input_helper);
+static void kgdboc_queue_restore_input_helper(struct irq_work *unused)
+{
+ schedule_work(&kgdboc_restore_input_work);
+}
+
+static DEFINE_IRQ_WORK(kgdboc_restore_input_irq_work, kgdboc_queue_restore_input_helper);
+
static void kgdboc_restore_input(void)
{
if (likely(system_state == SYSTEM_RUNNING))
- schedule_work(&kgdboc_restore_input_work);
+ irq_work_queue(&kgdboc_restore_input_irq_work);
}
static int kgdboc_register_kbd(char **cptr)
@@ -133,6 +160,7 @@ static void kgdboc_unregister_kbd(void)
i--;
}
}
+ irq_work_sync(&kgdboc_restore_input_irq_work);
flush_work(&kgdboc_restore_input_work);
}
#else /* ! CONFIG_KDB_KEYBOARD */