[LEAPSECS] happy anniversary pips

[Tim Shepard]

> >> People have been working for the past 15 years to make leap seconds

> >> better, yet in the last leap second all Linux kernels crashed due

> >> to a subtle bug that is only triggered when there was a leap second.

> >

> >My understanding wasn't that all Linux kernels crashed.

> 

> Only the ones which cared enough about time-keeping to run NTPD.


... and that were running a particular old-but-not-too-old version of
the Linux kernel.  And it didn't happen everywhere.  And it didn't
crash machines, just got them very busy looping blocked by in-kernel
locks (which is perhaps worse than a crash, depending on what
matters).

The patch to fix the bug was published in main-line Linux more than
three months before the leap second occured:

  https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6b43ae8a619d17c4935c3320d2ef9e92bdeed05d

but the patch didn't get deployed everywhere it needed to be deployed,
and the wedge up of some web site server farms made news:

  http://www.wired.com/wiredenterprise/2012/07/leap-second-glitch-explained/all/


			-Tim Shepard
			 shep at alum.mit.edu