On 8 September 2016 17:14:02 BST, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote:
>On 09/08/2016 10:15 AM, Gregor Boirie wrote:
>> Hi Lars,
>>
>> On 09/07/2016 08:13 PM, Lars-Peter Clausen wrote:
>>> On 09/07/2016 07:26 PM, Gregor Boirie wrote:
>>>> Using iio_device_unregister() on a device currently in use may
>stall
>>>> userspace process polling for data availability (poll syscall).
>>>>
>>>> If device has vanished before running the iio_buffer_fileops poll
>hook, the
>>>> latter will return empty poll event mask. Process will be stalled
>waiting
>>>> for events that will never come (if no timeout specified).
>>>>
>>>> This patch ensures iio_buffer_poll() returns POLLERR if device has
>just
>>>> been unregistered in order to properly notify userspace process
>something
>>>> wrong happened (such as removable device unplugged).
>>>>
>>>> Fixes: 1bdc029390 ("iio: industrialio-buffer: Fix iio_buffer_poll
>return
>>>> value")
>>>> Signed-off-by: Gregor Boirie <gregor.boirie@xxxxxxxxxx>
>>> Hi,
>>>
>>> Thanks for the patch. I agree with the solution, I don't quite agree
>with
>>> the description. In my opinion the current behavior is not
>necessarily a
>>> bug. Obviously there won't be a wakeup when the device has been
>removed
>>> since no new data will be generated. But there are other scenarios
>where
>>> this can happen as well (e.g. broken hardware). An application
>should be
>>> prepared to handle this and if it is interactive for example allow
>the user
>>> to interrupt the capture process.
>> Ok. What do you want me to do then ? Remove the "Fixes" tag ? Reword
>> something in the commit log ?
>> I'll merge the 2 patches as recommended by Jonathan anyway.
>
>I'd drop the Fixes tag and maybe change the subject to "Let poll report
>an
>error for unregistered devices"
Agreed.
I guess this is in the no one should notice from the ABI change point of view.
J
>
>--
>To unsubscribe from this list: send the line "unsubscribe linux-iio" in
>the body of a message to majordomo@xxxxxxxxxxxxxxx
>More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
--
To unsubscribe from this list: send the line "unsubscribe linux-iio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
