Re: [PATCH v2] epoll: Support for disabling items, and a self-test app.

On Tue, 16 Oct 2012 17:12:57 +0200
"Michael Kerrisk (man-pages)" [off-list ref] wrote:

On Thu, Aug 23, 2012 at 11:15 PM, Paton J. Lewis [off-list ref] wrote:

quoted

From: "Paton J. Lewis" <redacted>

Enhanced epoll_ctl to support EPOLL_CTL_DISABLE, which disables an epoll item.
If epoll_ctl doesn't return -EBUSY in this case, it is then safe to delete the
epoll item in a multi-threaded environment. Also added a new test_epoll self-
test app to both demonstrate the need for this feature and test it.

(There's a lot of background missing from this version of the patch
that was included in the previous version
[http://thread.gmane.org/gmane.linux.kernel/1311457]. It helps to
include the full rationale with a revised patch--best not to assume
that someone has the context of past mails when reading a revised
patch.)

I've taken a look at this patch as it currently stands in 3.7-rc1, and
done a bit of testing. (By the way, the test program
tools/testing/selftests/epoll/test_epoll.c does not compile...)

Thanks for this.  You raise significant issues.  If we can't get these
fully resolved over the next month or so, we should revert the patch so
this new API doesn't get released in 3.7.  I have queued a patch to do
this and shall maintain it while I watch developments...