Messages in this thread |  | | Date | Fri, 14 Dec 2012 15:29:25 +0100 | From | Alexander Holler <> | Subject | Re: [PATCH 4/4 v4] rtc: add rtc-driver for HID sensors of type time |
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Am 14.12.2012 15:15, schrieb 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.
Sorry for the noise. That INIT_COMPLETION() before the sensor...() does exactly that. So it's enough if I handle the different return situations of wait_for...().
I will just use if(wait...()<=0) return -EIO.
Regards,
Alexander
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