dbus_connection_send_with_reply_and_block eats 100% CPU then eventually times out

[Ralf Habacker]

Am 31.01.2015 um 05:04 schrieb Alex Brooks:
> Hi,
>
> I've been fighting for a long time with what now looks like a libdbus
> bug.
> I have a cut-down test program which calls a dbus method of
> wpa_supplicant at 100Hz, it does this happily for several hours then
> at some point the behaviour changes: any future calls sit at 100% CPU
> for 25sec then time out.
> I don't think the problem is on the wpa_supplicant side: other clients
> can simultaneously make this call without any problems, and restarting
> the client fixes it.
> [I'm running at 100Hz because the faster I run this loop, the faster
> it reproduces the problem.  CPU load sits below 20% before I hit the
> bug].
>
> I posted details and a sample program as a Qt bug report (I'm using
> the QDBus wrapper and thought it might be a Qt bug initially):
> https://bugreports.qt.io/browse/QTBUG-43550
>
> Does anyone have any thoughts?
I compiled the testcase on opensuse 13.1 x86_64 and did run:

sudo ./signalpoll
getNetDevObjectPath(wlan0)
getNetDevObjectPath : GetInterface result:  QDBusMessage(type=Error,
service="", error name="fi.w1.wpa_supplicant1.InterfaceUnknown", error
message="wpa_supplicant knows nothing about this interface.",
signature="", contents=([]) )
terminate called after throwing an instance of 'std::string'

Regards
 Ralf m