[Info-vax] QIO Writes to a mailbox

[VAXman- at SendSpamHere.ORG]

In article <j91ebq$fbc$2 at pcls6.std.com>, moroney at world.std.spaamtrap.com (Michael Moroney) writes:
>Steve Bainbridge <stephen_bainbridge at yahoo.co.uk> writes:
>
>>This code was written several years ago and I've been dumped on to
>>investigate and correct the issue we now very occasionally see. I'm
>>aware of the obvious missing check on the IOSB, but I can't say with
>>any certainty that this is causing the problem.
>
>You *must* check the IOSB status and make sure the operation is complete
>to ensure the operation was performed properly.  Especially when using
>QIO (no W).

Exactly.  However, he hasn't yet indicated where the IOSBs are allocated.
If it is on the stack in that routine invoking the $QIO or in any routine
calling it, all bets are off if that routine returns BEFORE the $QIO has
completed -- even if he DOES check the "IOSB".



>Not checking the status is almost certainly the cause of the problem.

Hey, but he's a C coder.  They dun't need no steenkin status checking.  
I've found asynchronicity a foreign concept to the average unix mind.
-- 
VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG

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