From: Syed Nayyar Waris <syednwaris@xxxxxxxxx>
[ Upstream commit 708d98932893cea609386cefdfd190f757f5a61c ]
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@xxxxxxxxx>
Fixes: 954ab5cc5f3e ("counter: 104-quad-8: Support Differential Encoder Cable Status")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/counter/104-quad-8.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
index aa13708c2bc30..9364dc188f8ff 100644
--- a/drivers/counter/104-quad-8.c
+++ b/drivers/counter/104-quad-8.c
@@ -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;
}
--
2.25.1
