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SubjectRe: [PATCH 1/4] iio: dht11: Add locking
Am 14.12.2014 um 13:31 schrieb Hartmut Knaack:
> Richard Weinberger schrieb am 03.12.2014 um 00:32:
>> Make sure that the read function is not interrupted...
> There is already a mutex iio_dev->info_exist_lock used to serialize
> iio_channel_read(), which in turn accesses _read_raw(). See [1].
>
> [1]http://lxr.free-electrons.com/ident?i=iio_channel_read

This is only for the in-kernel API and not for sysfs access.
I.e. if you access via sysfs it is not protected.

Thanks,
//richard

>> Signed-off-by: Richard Weinberger <richard@nod.at>
>> ---
>> drivers/iio/humidity/dht11.c | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/iio/humidity/dht11.c b/drivers/iio/humidity/dht11.c
>> index d8771f5..168ebc4 100644
>> --- a/drivers/iio/humidity/dht11.c
>> +++ b/drivers/iio/humidity/dht11.c
>> @@ -29,6 +29,7 @@
>> #include <linux/wait.h>
>> #include <linux/bitops.h>
>> #include <linux/completion.h>
>> +#include <linux/mutex.h>
>> #include <linux/delay.h>
>> #include <linux/gpio.h>
>> #include <linux/of_gpio.h>
>> @@ -57,6 +58,7 @@ struct dht11 {
>> int irq;
>>
>> struct completion completion;
>> + struct mutex lock;
>>
>> s64 timestamp;
>> int temperature;
>> @@ -145,6 +147,7 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
>> struct dht11 *dht11 = iio_priv(iio_dev);
>> int ret;
>>
>> + mutex_lock(&dht11->lock);
>> if (dht11->timestamp + DHT11_DATA_VALID_TIME < iio_get_time_ns()) {
>> reinit_completion(&dht11->completion);
>>
>> @@ -185,6 +188,7 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
>> ret = -EINVAL;
>> err:
>> dht11->num_edges = -1;
>> + mutex_unlock(&dht11->lock);
>> return ret;
>> }
>>
>> @@ -268,6 +272,7 @@ 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;
>>
>


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