[PATCH 3.16 211/370] sysrq: attach sysrq handler correctly for 32-bit kernel

From: Ben Hutchings
Date: Fri Mar 10 2017 - 08:59:40 EST


3.16.42-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Akinobu Mita <akinobu.mita@xxxxxxxxx>

commit 802c03881f29844af0252b6e22be5d2f65f93fd0 upstream.

The sysrq input handler should be attached to the input device which has
a left alt key.

On 32-bit kernels, some input devices which has a left alt key cannot
attach sysrq handler. Because the keybit bitmap in struct input_device_id
for sysrq is not correctly initialized. KEY_LEFTALT is 56 which is
greater than BITS_PER_LONG on 32-bit kernels.

I found this problem when using a matrix keypad device which defines
a KEY_LEFTALT (56) but doesn't have a KEY_O (24 == 56%32).

Cc: Jiri Slaby <jslaby@xxxxxxxx>
Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Acked-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
drivers/tty/sysrq.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -933,8 +933,8 @@ static const struct input_device_id sysr
{
.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
INPUT_DEVICE_ID_MATCH_KEYBIT,
- .evbit = { BIT_MASK(EV_KEY) },
- .keybit = { BIT_MASK(KEY_LEFTALT) },
+ .evbit = { [BIT_WORD(EV_KEY)] = BIT_MASK(EV_KEY) },
+ .keybit = { [BIT_WORD(KEY_LEFTALT)] = BIT_MASK(KEY_LEFTALT) },
},
{ },
};