Re: calcout/scalcout record problem in EPICS 3.14.7

[Andrew Johnson <anj@aps.anl.gov>]

Tim,

Tim Mooney wrote:
> The calcout record in EPICS 3.14.7 (and
> maybe other versions as well -- probably all versions since the record
> acquired asynchronous device support) has a problem that results in an
> infinite loop if two calcout records forward link to each other.

Ouch:

epics> dbpf anjHost:a.TPRO 1
DBR_UCHAR:          1         0x1
epics> dbpf anjHost:a.PROC 1
_main_: Process anjHost:a
_main_: Process anjHost:b
_main_: Process anjHost:a
...
_main_: Process anjHost:a
_main_: Process anjHost:b
_main_: Process anjHost:a
Segmentation fault

That was the main thread's stack overflowing, since each forward link 
involves a recursive call to process the next record in the chain.

I agree with your fix, and I've committed the modified calcRecord.c to 
CVS.  Asynchronous device support was added to the calcRecord in R3.14.5 
so versions or Base before that release are not susceptible to this 
problem.  There's a patch available that is linked from the R3.14.8 
KnownProblems page for anyone who wants to apply it.

- Andrew
--
There is no S in exprexxo.