[systemd-devel] [PATCH v2 00/26] Initial DHCP v4 library implementation

[Patrik Flykt]

On Mon, 2013-11-25 at 23:52 +0100, Lennart Poettering wrote:
> Of course, timer callbacks should only be called once, ence
> ONESHOT mode is the default -- unless you change that explicitly.
> 
> If this doesn't solve the issue, I wouldn't be surprised if there was
> still a bug lurking with the sd-event code. Note that I fixed a bug
> like this last week, did you check with currentl git of sd-event if
> the issue persists?

Found the source of this issue. When the (monotonic) timeout function is
called with time 0 meaning "immediately", the callback indeed gets
called next by the event loop. But the uint64_t usec value passed to the
timer callback is the value 0 set by the caller, not the current
monotonic time the callback is called at. Using the supplied usec value,
which is 0, as a base when calculating the next event timeout results of
course in a time very much smaller time than the current monotonic time,
causing the callback to be called immediately again. The value is again
the one set by the caller and thus the calculated time is again too low.
Rinse and repeat.

I fixed the problem by using sd_event_get_now_monotonic() instead of the
supplied usec value as it wasn't clear what the intended behavior was.
systemd upstream version tested was from approximately last Friday
should something have changed recently.

Cheers,

	Patrik