Re: [PATCHv3 linux-next] hrtimer: Add notifier when clock_was_set was called

[David Miller <davem@davemloft.net>]

From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 12 Sep 2013 16:43:37 +0200 (CEST)

> So what about going back to timer_list timers and simply utilize
> register_pm_notifier(), which will tell you that the system resumed?

The thing to understand is that there are two timeouts for an IPSEC
rule, a soft and a hard timeout.

There is a gap between these two exactly so that we can negotiate a
new encapsulation with the IPSEC gateway before communication ceases
to be possible over the IPSEC protected path.

So the idea is that the soft timeout triggers the re-negotiation,
and after a hard timeout the IPSEC path is no longer usable and
all communication will fail.

Simply triggering a re-negoation after every suspend/resume makes
no sense at all.  Spurious re-negotiations are undesirable.

What we want are real timers.  We want that rather than a "we
suspended so just assume all timers expired" event which is not very
useful for this kind of application.