On my (OpenWRT) router, I have an "/etc/init.d/shorewall-lite
restart" (which effectively is shorewall-lite restore) executed during
an "interface transition" (i.e. up/down) event.  This is to allow
shorewall to adjust the rules and/or routing when an interface changes
state.  TBH, I don't so much care about the interface down event as much
as I care about an interface coming up when shorewall was restarted with
an interface being down.  But I digress.

The ugly side effect of this is that when the router initially boots,
lots of "interface up" events are triggered and thus many
"overlapping"/parallel shorewall-lite restore commands are run.  This is
silly of course[1].

My knee-jerk reaction is to simply have shorewall-lite exit if there is
an instance running already, but given more thought, that seems
backwards.  The earlier instance might have already assessed the
interface for which the new instance is being called and thus, the
earlier instance has a stale view of the interface status.  So it seems
the right thing to do is for the new instance to kill the earlier
instance before it (the new instance) starts doing it's thing.  This
would continue to happen until the last of the initial boot "interface
up" events runs to completion.

Thots?

b.

[1] It might seem pretty harmless to have a number of parallel executing
shorewall-lite restore processes running given that I recall seeing some
locking/timeout code in there to prevent more than one from actually
going through their processing in parallel but on a limited memory
machine, it would seem that the effect of this is ooms.  :-(

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