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

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Message-ID: <lsq.1527677561.921791136@decadent.org.uk>
Date:   Wed, 30 May 2018 11:52:41 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Dmitry Torokhov" <dmitry.torokhov@...il.com>,
        "Zhang Bo" <zbsdta@....com>
Subject: [PATCH 3.2 082/153] Input: matrix_keypad - fix race when
 disabling interrupts

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

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

From: Zhang Bo <zbsdta@....com>

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@....com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 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;