counter: 104-quad-8: Add lock guards - filter clock prescaler

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@gmail.com>
Fixes: de65d0556343 ("counter: 104-quad-8: Support Filter Clock Prescaler")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
index 9364dc188f8ff60cb172c45a5d23f155f462c44b..d22cfae1b0198922c212ee08d491393f904bb3de 100644 (file)
--- 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;
 }