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sysrq: attach sysrq handler correctly for 32-bit kernel
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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@suse.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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mita authored and gregkh committed Jan 11, 2017
1 parent 6741f55 commit 802c038
Showing 1 changed file with 2 additions and 2 deletions.
4 changes: 2 additions & 2 deletions drivers/tty/sysrq.c
Original file line number Diff line number Diff line change
Expand Up @@ -946,8 +946,8 @@ static const struct input_device_id sysrq_ids[] = {
{
.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) },
},
{ },
};
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