From: Syed Nayyar Waris syednwaris@gmail.com
[ 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@gmail.com Fixes: 954ab5cc5f3e ("counter: 104-quad-8: Support Differential Encoder Cable Status") Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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; }