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

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Message-ID: <lsq.1489146383.267349859@decadent.org.uk>
Date:   Fri, 10 Mar 2017 11:46:23 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Akinobu Mita" <akinobu.mita@...il.com>,
        "Jiri Slaby" <jslaby@...e.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Dmitry Torokhov" <dmitry.torokhov@...il.com>
Subject: [PATCH 3.16 211/370] sysrq: attach sysrq handler correctly for
 32-bit kernel

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

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

From: Akinobu Mita <akinobu.mita@...il.com>

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@...e.com>
Signed-off-by: Akinobu Mita <akinobu.mita@...il.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 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) },
 	},
 	{ },
 };