On Tue, Apr 24, 2018 at 02:53:38PM +0100, Richard Hill wrote:
>
>
> I am getting a dst NULL pointer here (in port_delay_request)
>
> if (p->hybrid_e2e) {
> struct ptp_message *dst = TAILQ_FIRST(&p->best->messages);
> msg->address = dst->address;
> msg->header.flagField[0] |= UNICAST;
> }
> This appears to be because the list is empty
> So is it enough just to add a check for n_messages - eg
That would not be wrong, BUT...
> Or should the list never be empty at this point ?
The list can't be empty. Here is why.
The function, port_delay_request(), is called only when FD_DELAY_TIMER
expires.
That timer is only set by the function, port_set_delay_tmo(), which is
called:
1. in process_delay_resp() but only when state is UNCALIBRATED or SLAVE.
2. in port_e2e_transition() but only when state is UNCALIBRATED or SLAVE.
Looking at handle_state_decision_event(), a port can only enter
UNCALIBRATED or SLAVE when it has a valid foreign master record, ie
p->best->messages is not null.
A port also only clears p->best->messages when it leaves UNCALIBRATED
or SLAVE, at which point the FD_DELAY_TIMER is also cleared.
So we have overlooked something...
What version are you running?
The source is unmodified, right?
Thanks,
Richard
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