Re: [Xen-devel] [PATCH v2 10/10] libxl: event: Move poller pipe emptying to the end of afterpoll

[Ian Jackson <ian.jackson@xxxxxxxxxx>]

Ian Jackson writes ("Re: [PATCH v2 10/10] libxl: event: Move poller pipe 
emptying to the end of afterpoll"):
> TBH I still think this patch tidies the code up a bit.

Given you tested it with this change, and I think it makes it a bit
tidier and no less correct, I would like to keep it.

I rewrote the commit message - see below.

Ian.

libxl: event: Move poller pipe emptying to the end of afterpoll

This seems neater.  It doesn't have any significant effect because:

The poller fd wouldn't be emptied by time_occurs.  It would only be
woken by time_occurs as a result of an ao completing, or by
libxl__egc_ao_cleanup_1_baton.  But ...1_baton won't be called in
between (for one thing, this would violate the rule of not still
having the active caller when ...1_baton is called).

While discussing this patch, I noticed that there is a possibility (in
libxl in general) that poller_put might be called on a woken poller.
It would probably be sensible at some point to make poller_get empty
the pipe, at least if the pipe_nonempty flag is set.

Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Tested-by: George Dunlap <george.dunlap@xxxxxxxxxx>
---
v2: Completely revised commit message; now we think this is just
    cleanup.

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