linux-kernel - [PATCH 5.7 079/244] counter: 104-quad-8: Add lock guards

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Date:   Mon, 20 Jul 2020 17:35:50 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Syed Nayyar Waris <syednwaris@...il.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.7 079/244] counter: 104-quad-8: Add lock guards - filter clock prescaler

From: Syed Nayyar Waris <syednwaris@...il.com>

[ Upstream commit d5ed76adb926a90fada98f518abc1ab6ef07d28f ]

Add lock protection from race conditions to the 104-quad-8 counter
driver for filter clock prescaler code changes. Mutex calls used for
protection.

Signed-off-by: Syed Nayyar Waris <syednwaris@...il.com>
Fixes: de65d0556343 ("counter: 104-quad-8: Support Filter Clock Prescaler")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/counter/104-quad-8.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
index 9364dc188f8ff..d22cfae1b0198 100644
--- a/drivers/counter/104-quad-8.c
+++ b/drivers/counter/104-quad-8.c
@@ -1365,6 +1365,8 @@ static ssize_t quad8_signal_fck_prescaler_write(struct counter_device *counter,
 	if (ret)
 		return ret;
 
+	mutex_lock(&priv->lock);
+
 	priv->fck_prescaler[channel_id] = prescaler;
 
 	/* Reset Byte Pointer */
@@ -1375,6 +1377,8 @@ static ssize_t quad8_signal_fck_prescaler_write(struct counter_device *counter,
 	outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_PRESET_PSC,
 	     base_offset + 1);
 
+	mutex_unlock(&priv->lock);
+
 	return len;
 }
 
-- 
2.25.1