Pull timer fixes from Thomas Gleixner:
"Two fixes from the timer departement:
- Fix a long standing issue in the NOHZ tick code which causes RB
tree corruption, delayed timers and other malfunctions. The cause
for this is code which modifies the expiry time of an enqueued
hrtimer.
- Revert the CLOCK_MONOTONIC/CLOCK_BOOTTIME unification due to
regression reports. Seems userspace _is_ relying on the documented
behaviour despite our hope that it wont"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Revert: Unify CLOCK_MONOTONIC and CLOCK_BOOTTIME
tick/sched: Do not mess with an enqueued hrtimer
