tree be40f26754c79d03cb335b8fd14b669a2cce7416
parent 00b0fb9349b8842a5ec2cee9dc4f286c8d3a3685
author Willy Tarreau <w@1wt.eu> 1390245539 +0100
committer Willy Tarreau <w@1wt.eu> 1390247822 +0100
encoding latin1

BUG/MEDIUM: polling: ensure we update FD status when there's no more activity

Some rare unexplained busy loops were observed on versions up to 1.5-dev19.
It happens that if a file descriptor happens to be disabled for both read and
write while it was speculatively enabled for both and this without creating a
new update entry, there will be no way to remove it from the speculative I/O
list until some other changes occur. It is suspected that a double sequence
such as enable_both/disable_both could have led to this situation where an
update cancels itself and does not clear the spec list in the poll loop.
While it is unclear what I/O sequence may cause this situation to arise, it
is safer to always add the FD to the update list if nothing could be done on
it so that the next poll round will automatically take care of it.

This is 1.5-specific, no backport is needed.