[PATCH 3.2 082/153] Input: matrix_keypad - fix race when disabling interrupts

From: Ben Hutchings
Date: Wed May 30 2018 - 07:20:58 EST


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

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

From: Zhang Bo <zbsdta@xxxxxxx>

commit ea4f7bd2aca9f68470e9aac0fc9432fd180b1fe7 upstream.

If matrix_keypad_stop() is executing and the keypad interrupt is triggered,
disable_row_irqs() may be called by both matrix_keypad_interrupt() and
matrix_keypad_stop() at the same time, causing interrupts to be disabled
twice and the keypad being "stuck" after resuming.

Take lock when setting keypad->stopped to ensure that ISR will not race
with matrix_keypad_stop() disabling interrupts.

Signed-off-by: Zhang Bo <zbsdta@xxxxxxx>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
drivers/input/keyboard/matrix_keypad.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/input/keyboard/matrix_keypad.c
+++ b/drivers/input/keyboard/matrix_keypad.c
@@ -214,8 +214,10 @@ static void matrix_keypad_stop(struct in
{
struct matrix_keypad *keypad = input_get_drvdata(dev);

+ spin_lock_irq(&keypad->lock);
keypad->stopped = true;
- mb();
+ spin_unlock_irq(&keypad->lock);
+
flush_work(&keypad->work.work);
/*
* matrix_keypad_scan() will leave IRQs enabled;