On 07/08/2011 09:16 AM, Becky Ligon wrote:
Good point, Phil.
Before Sam's bug fix, the free(op-entry) was in the complete-op function.
However, he didn't have the unregister() and I don't know why. So, maybe,
putting the unregister() and free() outside of complete-op() IS the better
way to handle it. It seems that there never was an unregister() and I'm
wondering if that could have been causing problems as well, i.e., one
reason why the bug fix was needed in the first place.
Becky
There were two related issues here. The first was switching from
fast_register to safe_register, which if I understand correctly was done
to prevent a possible segfault if someone tried to access an operation
id that had already been completed. (the fast one is "fast" rather than
"safe" because it does no error checking and will map whatever ID you
give it to a pointer in memory whether it is valid or not; you can only
use it when you are confident about how the IDs will be used by
callers). There is another difference between those two ID generators,
though: the fast_register doesn't technically need matching unregister
calls because the fast_unregister is a noop, but safe_register _does_
require matching unregister calls to free some book keeping data
structures. That's why those unregisters were added as part of that
change. In the original code it would have been better to use the
unregister calls just for symmetry, but it wasn't hurting anything to
leave them out.
-Phil
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