Protect the read function from concurrent reads.
Signed-off-by: Richard Weinberger <rich...@nod.at>
---
drivers/iio/humidity/dht11.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/iio/humidity/dht11.c b/drivers/iio/humidity/dht11.c
index 623c145..7636e66 100644
--- a/drivers/iio/humidity/dht11.c
+++ b/drivers/iio/humidity/dht11.c
@@ -57,6 +57,7 @@ struct dht11 {
int irq;
struct completion completion;
+ struct mutex lock;
s64 timestamp;
int temperature;
@@ -146,16 +147,17 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
int ret;
if (dht11->timestamp + DHT11_DATA_VALID_TIME < iio_get_time_ns()) {
+ mutex_lock(&dht11->lock);
reinit_completion(&dht11->completion);
dht11->num_edges = 0;
ret = gpio_direction_output(dht11->gpio, 0);
if (ret)
- goto err;
+ goto err_unlock;
msleep(DHT11_START_TRANSMISSION);
ret = gpio_direction_input(dht11->gpio);
if (ret)
- goto err;
+ goto err_unlock;
ret = wait_for_completion_killable_timeout(&dht11->completion,
HZ);
@@ -166,14 +168,16 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
ret = -ETIMEDOUT;
}
if (ret < 0)
- goto err;
+ goto err_unlock;
ret = dht11_decode(dht11,
dht11->num_edges == DHT11_EDGES_PER_READ ?
DHT11_EDGES_PREAMBLE :
DHT11_EDGES_PREAMBLE - 2);
+
+ mutex_unlock(&dht11->lock);
if (ret)
- goto err;
+ goto out;
}
ret = IIO_VAL_INT;
@@ -183,9 +187,13 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
*val = dht11->humidity;
else
ret = -EINVAL;
-err:
+out:
dht11->num_edges = -1;
return ret;
+
+err_unlock:
+ mutex_unlock(&dht11->lock);
+ goto out;
}
static const struct iio_info dht11_iio_info = {
@@ -268,6 +276,7 @@ static int dht11_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, iio);
init_completion(&dht11->completion);
+ mutex_init(&dht11->lock);
iio->name = pdev->name;
iio->dev.parent = &pdev->dev;
iio->info = &dht11_iio_info;
--
2.1.0
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