[systemd-devel] [PATCH 2/2] udev: Allow detection of udevadm settle timeout

[Nir Soffer]

On Tue, Apr 21, 2015 at 12:41 AM, Tom Gundersen <teg at jklm.no> wrote:
> On Mon, Apr 13, 2015 at 3:04 PM, Nir Soffer <nirsof at gmail.com> wrote:
>> On Sat, Apr 11, 2015 at 6:58 PM, David Herrmann <dh.herrmann at gmail.com> wrote:
>>>> A program running this tool can detect a timeout (expected) or an error
>>>> (unexpected), and can change the program flow based on this result.
>>>>
>>>> Without this, the only way to detect a timeout is to implement the timeout
>>>> in the program calling udevadm.
>>>
>>> I cannot really see a use-case here. I mean, yeah, the commit-message
>>> says it warns about timeouts but fails loudly on real errors. But
>>> again, what's the use-case? Why is a timeout not a real error? Why do
>>> you need to handle it differently?
>>
>> Timeout means that the value I chose may be too small, or the machine
>> is overloaded. The administrator may need to configure the system
>> differently.
>>
>> Other errors are not expected, and typically unexpected errors in an
>> underlying tool means getting the developer of the underlying tool
>> involved.
>>
>>> Anyway, if it's only about diagnostics this patch seems fine to me.
>>
>> Yes, it is mainly about diagnostics, and making it easier to debug and support.
>
> Wouldn't a better solution be to improve the udevadm logging? If we
> change the exit codes this is basically ABI. Do we really want to make
> such promises only for diagnostics?

Improving logging is orthogonal, as it does allow the program to change
the flow based the exit code.

Adding a timeout exit code may break code using undocumented behavior,
since the return code is not documented.

Nir