[dtrace-discuss] Error trying to count return points in functions.

[Darren.Reed at Sun.COM]

Whilst trying out some D to get an insight into what is the most
common reason for a given function to return, I have bumped
into an error I don't understand.

The first take on what I was trying to do was:
# dtrace -n 'fbt:ip:ip_input:return{@home[arg0] = count();}'

and all was well.  The next step was:
# dtrace -n 'fbt:ip::return{@home[strjoin(probefunc,(string)arg0)] = 
count();}'

but the output was not quite so friendly:
dtrace: description 'fbt:ip::return' matched 1653 probes
dtrace: error on enabled probe ID 1574 (ID 23867: 
fbt:ip:ip_loopback_src_or_dst:return): invalid address (0x30) in action 
#2 at DIF offset 48
dtrace: error on enabled probe ID 769 (ID 25479: 
fbt:ip:ilm_lookup_ill:return): invalid address (0x52) in action #2 at 
DIF offset 48
...

and all is not well.  I've also tried stringof(arg0) but the result is 
similar.
By way of testing, @home[probefunc] worked fine.

Is this a bug (fixed in nevada?) or am I just not supposed to do this?

Darren