Hi Richard,
thanks for the patch. Comments inline.
Richard Weinberger writes:
> Protect the read function from concurrent reads.
>
> Signed-off-by: Richard Weinberger <richard@xxxxxx>
> ---
> 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
#include <linux/mutex.h>
> @@ -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);
Move the locking out of the if statement.
BTW, it seems that there is already locking around read_raw() in the
in-kernel consumer interface but not in the sysfs interface. Is there
any reason for this difference?
Thanks,
Harald
> 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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