[Ovmsdev] Crashing on restart

[Michael Balzer]

The log shows it actually crashes during the shutdown process -- but 
@Michael, I'm pretty sure this is an old issue, turning up now only by 
chance.

This looks like a race condition between event handler invocation and 
deregistration:

Guru Meditation Error: Core  1 panic'ed (InstrFetchProhibited).Exception 
was unhandled.
…
Backtrace: 0x41000000:0x3ffc8c30 0x401208ed:0x3ffc8c60 
0x401209d4:0x3ffc8cc0 0x40120a5d:0x3ffc8d00

→ Crash at *0x41000000* (invalid address), called from:

0x401208ed is in OvmsEvents::HandleQueueSignalEvent(event_queue_t*) 
(/home/balzer/esp/Open-Vehicle-Monitoring-System-3/vehicle/OVMS.V3/main/ovms_events.cpp:310).
305           {
306           for (EventCallbackList::iterator itc=el->begin(); 
itc!=el->end(); ++itc)
307             {
308             m_current_started = monotonictime;
309             m_current_callback = *itc;
*310 m_current_callback->m_callback(m_current_event, 
msg->body.signal.data);*
311             m_current_callback = NULL;
312             }
313           }
314         }

 From there it then enters a crash loop from the crash handler somehow 
running into an illegal address when trying to access the RTC boot_data 
object (?).


I think, when introducing the separate event handling task, we missed 
adding a lock to make manipulations & accesses to the event handler list 
atomic.

The log shows, the event queue grew significantly due to duktape/scripts 
lagging during shutdown (as seen in the log), so the task was quite busy.

So probably a `DeregisterEvent()` call from the shutdown process came 
in, invalidating a callback entry just while the event task was 
processing that callback list.

Solving this may need some additional thoughts & measures: locking the 
whole event registry with handlers lagging like this could lead to a 
deadlock… probably at least the Duktape component needs to cleanly 
abort/reject all pending events before/while deregistering.

Michael, if you'd like to have a look at this, go ahead.

Regards,
Michael


Am 01.01.25 um 11:47 schrieb Tamás Kovács via OvmsDev:
> Now i change the sd card to a smaller, and formatted to fat32 (16Gb), 
> but on reboot is crashing.
> Now connect a computer to the usb port, and create a log in verbose, 
> attached to the email.
>
>
> -- 
> Üdvözlettel:
> Kovács Tamás
>
>
> _______________________________________________
> OvmsDev mailing list
> OvmsDev at lists.openvehicles.com
> http://lists.openvehicles.com/mailman/listinfo/ovmsdev

-- 
Michael Balzer * Am Rahmen 5 * D-58313 Herdecke
Fon 02330 9104094 * Handy 0176 20698926

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