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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Zhang Bo <zbsdta@126.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: [PATCH 4.14 082/140] Input: matrix_keypad - fix race when disabling interrupts
Date:   Tue, 13 Mar 2018 16:24:45 +0100
Message-Id: <20180313152503.702069224@linuxfoundation.org>
In-Reply-To: <20180313152458.201155692@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Zhang Bo <zbsdta@126.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@126.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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
@@ -218,8 +218,10 @@ 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;