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counter: 104-quad-8: Add lock guards - differential encoder

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Add lock protection from race conditions to 104-quad-8 counter driver
for differential encoder status code changes. Mutex lock calls used for
protection.

Signed-off-by: Syed Nayyar Waris <syednwaris@gmail.com>
Fixes: 954ab5cc5f ("counter: 104-quad-8: Support Differential Encoder Cable Status")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Syed Nayyar Waris 2020-03-16 18:20:06 +05:30 committed by Jonathan Cameron
parent 25f02d3242
commit 708d989328
1 changed files with 15 additions and 3 deletions
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18
drivers/counter/104-quad-8.c
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@ -1274,18 +1274,26 @@ static ssize_t quad8_signal_cable_fault_read(struct counter_device *counter,
struct counter_signal *signal,
void *private, char *buf)
{
const struct quad8_iio *const priv = counter->priv;
struct quad8_iio *const priv = counter->priv;
const size_t channel_id = signal->id / 2;
const bool disabled = !(priv->cable_fault_enable & BIT(channel_id));
bool disabled;
unsigned int status;
unsigned int fault;
if (disabled)
mutex_lock(&priv->lock);
disabled = !(priv->cable_fault_enable & BIT(channel_id));
if (disabled) {
mutex_unlock(&priv->lock);
return -EINVAL;
}
/* Logic 0 = cable fault */
status = inb(priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);
mutex_unlock(&priv->lock);
/* Mask respective channel and invert logic */
fault = !(status & BIT(channel_id));
@ -1317,6 +1325,8 @@ static ssize_t quad8_signal_cable_fault_enable_write(
if (ret)
return ret;
mutex_lock(&priv->lock);
if (enable)
priv->cable_fault_enable |= BIT(channel_id);
else
@ -1327,6 +1337,8 @@ static ssize_t quad8_signal_cable_fault_enable_write(
outb(cable_fault_enable, priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);
mutex_unlock(&priv->lock);
return len;
}