Re: udev: Why non-blocking poll() with blocking recvmsg()?

Martin Pitt <[email protected]>
Newsgroups org.kernel.vger.linux-hotplug
Message-ID <[email protected]> 
Hello Tetsuo,

Tetsuo Handa [2013-08-19 20:39 +0900]:
> I'm experiencing a boot failure problem with wait-for-root utility in Ubuntu 12.04.

Note that this is an Ubuntu specific program.

> Although wait-for-root uses blocking socket, udev_monitor_receive_device() sometimes
> immediately returns NULL.

It *assumed* a blocking socket, but didn't make sure that it actually
was. Originally libudev used blocking sockets, but at some point [1]
this was switched to non-blocking by default, and wait-for-root needed
to be adjusted to that. Please see https://launchpad.net/bugs/1154813,
it's fixed in newer Ubuntu releases.

[1] http://git.kernel.org/cgit/linux/hotplug/udev.git/commit/?idd83b8

Martin
-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)
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