Harald,
Am 02.12.2014 um 11:07 schrieb Harald Geyer:
> 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.
Care to explain why?
But I found another issue in my patch.
The "dht11->num_edges = -1;" before "return ret" needs to go into the locked area.
Will send an updated version soon.
> 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?
Dunno. :-)
Thanks,
//richard
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