Re: Issue with cancel_before_shmem_exit while searching to remove a particular registered exit callbacks

On Thu, Aug 6, 2020 at 11:46 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
> I sent the patch previously[1], but attaching here again, modifies
> cancel_before_shmem_exit() function comment to reflect the safe usage
> of before_shmem_exit_list callback mechanism and also removes the
> point "For simplicity, only the latest entry can be removed*********"
> as this gives a meaning that there is still scope for improvement in
> cancel_before_shmem_exit() search mechanism.
>
> Thoughts?

I think that the first part of the comment change you suggest is a
good idea and would avoid developer confusion, but I think that the
statement about unordered removal of comments being risky doesn't add
much. It's too vague to help anybody and I don't think I believe it,
either. So I suggest something more like:

- * callback. For simplicity, only the latest entry can be
- * removed. (We could work harder but there is no need for
- * current uses.)
+ * callback. We only look at the latest entry for removal, as we
+ * expect the caller to use before_shmem_exit callback mechanism
+ * in the LIFO order.

--
Robert Haas
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