The Debian init system general resolution returns

Posted Nov 2, 2014 15:28 UTC (Sun) by nix (subscriber, #2304)
In reply to: The Debian init system general resolution returns by Cyberax
Parent article: The Debian init system general resolution returns

Throttle the senders? So now consumers of this information get a randomly inaccurate mount table! That's ever so much better.

Or they could read /proc/self/mounts or /proc/self/mountinfo and get an always-reliable, namespace-aware view with none of this nonsense.

The Debian init system general resolution returns

Posted Nov 2, 2014 17:09 UTC (Sun) by Cyberax (✭ supporter ✭, #52523) [Link] (1 responses)

Any asynchronous interface (yes, including udev over netlink sockets) is susceptible to receiving stale data. And even reading /proc/mounts is racy, because anything can happen after you do a 'read' call.

Besides, netlink sockets can block senders just as well as kdbus.

The Debian init system general resolution returns

Posted Nov 2, 2014 17:31 UTC (Sun) by viro (subscriber, #7872) [Link]

... and PID 1 is never ever going to do _blocking_ send, regardless of the transport. Think what happens with the system where PID 1 is fast asleep... There's a damn good reason why systemd doesn't do blocking sendmsg(). The problem isn't transport one; it's that in congested situations you need to change the traffic you are generating. And sending the mount table updates is completely pointless, congested situation or not.