Re: [PATCH 4/4 v4] rtc: add rtc-driver for HID sensors of type time

[Alexander Holler]

Am 14.12.2012 14:08, schrieb Alexander Holler:
> Am 14.12.2012 10:42, schrieb Lars-Peter Clausen:

> > And another thing I've overlooked before:
> > wait_for_completion_interruptible_timeout can either return a positive
> > number when the completion was completed, 0 in case of an timeout, or a
> > negative error code in case it was interrupted. You need to handle all
> > three. E.g. something like this.
> >
> > ret = wait_for_completion_interruptible_timeout(...)
> > if (ret == 0)
> >     return -EIO;
> > if (ret < 0)
> >     return ret
>
> Hmpf, the only working approach to use some in kernel functions really
> is to the read source yourself and don't trust anything else. :/

Anyway, my approach doesn't work as it introduces a race condition:


/* get a report with all values through requesting one value */
sensor_hub_input_attr_get_raw_value(...)

/* race if this task goes to slepp and the values were
received before it could call the below wait...

/* wait for all values (event) */
if (!wait_for_completion_interruptible_timeout(...))


I'll have to look for a mechanism how to avoid that. So v5 might need 
some time.


Regards,

Alexander

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