Here is my attempt on a fix for bug 70181, please review it. It is
tested on my nordic Corsair K70, if this solution is deemed acceptable
I can ask some people with other problematic keyboards to test it.

Signed-off-by: Fredrik Hallenberg <redacted>
---
 drivers/hid/hid-input.c | 14 ++++++++++++++
 include/linux/hid.h     |  1 +
 2 files changed, 15 insertions(+)

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 2619f7f..56429c0 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c

@@ -1085,6 +1085,20 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct
                return;
        }

+       /*
+        * Some keyboards will report both HID keys 0x31 (\ and |) and
+        * 0x32 (Non-US # and ~) which are both mapped to
+        * KEY_BACKSLASH. This will cause spurious events causing
+        * repeated backslash key presses. Handle this by tracking the
+        * active HID code and ignoring the other one.
+        */
+       if (usage->type == EV_KEY && usage->code == KEY_BACKSLASH) {
+               if (value)
+                       field->hidinput->backslash_usage = usage->hid;
+               else if (field->hidinput->backslash_usage != usage->hid)
+                       return;
+       }
+
        /* report the usage code as scancode if the key status has changed */
        if (usage->type == EV_KEY && !!test_bit(usage->code, input->key) != value)
                input_event(input, EV_MSC, MSC_SCAN, usage->hid);

diff --git a/include/linux/hid.h b/include/linux/hid.h
index f53c4a9..1c59f8f 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h

@@ -448,6 +448,7 @@ struct hid_input {
        struct list_head list;
        struct hid_report *report;
        struct input_dev *input;
+       unsigned backslash_usage;
 };

 enum hid_type {
--

2.1.0.rc1